Add location search, home/fit map buttons, and slim OSM attribution

- TopNavBar: Nominatim geocoding search field plus Home (center on first
  waypoint) and Fit (zoom to mission bounds) buttons (HTML prototype:
  #searchWrap/#homeBtn/#fitBtn). Both show a SnackBar instead of doing
  nothing when there are no waypoints yet.
- Renders as its own bar just below TopModeBar rather than fused into the
  same pill: TopModeBar lives in AppShell, a layer above PlanScreen, which
  owns the MapController these actions actually need. Fusing them would
  need lifting the MapController to shared state - reasonable follow-up
  if pixel-fidelity with the prototype's single bar matters later, but
  not necessary for the functionality itself.
- Replaced SimpleAttributionWidget with a compact custom attribution: OSM's
  tile usage policy requires visible attribution to stay, so instead of
  removing it (as first asked) I shrank it and dropped the "flutter_map |"
  prefix per the user's follow-up choice, so it reads cleanly against the
  now-opaque bottom bar instead of looking like a second banner.

Added 5 tests (nav bar renders, home/fit SnackBars with no waypoints,
empty search is a no-op). All 26 tests and flutter analyze pass. Verified
on the Pixel_10a emulator: searched "Berlin" and confirmed the map flew
there, dropped a waypoint, panned far away, and confirmed Home re-centers
and snaps onto it exactly.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/lib/ui/screens/plan/plan_screen.dart

@@ -1,9 +1,11 @@
 import 'dart:async';
+import 'dart:convert';
 import 'dart:math' as math;
 
 import 'package:flutter/material.dart';
 import 'package:flutter_map/flutter_map.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:http/http.dart' as http;
 import 'package:latlong2/latlong.dart';
 
 import '../../../domain/mission/default_drone_profile.dart';
@@ -15,6 +17,7 @@ import '../../widgets/halo_menu.dart';
 import '../../widgets/mini_altitude_profile.dart';
 import '../../widgets/mission_map.dart';
 import '../../widgets/reticle_button.dart';
+import '../../widgets/top_nav_bar.dart';
 import '../../widgets/value_wheel.dart';
 import '../../widgets/waypoint_list_panel.dart';
 
@@ -254,6 +257,68 @@ class _PlanScreenState extends ConsumerState<PlanScreen> {
     _handleMoveEnd();
   }
 
+  /// Ortssuche per Nominatim-Geocoding (HTML-Demonstrator: doSearch()).
+  /// Zentriert die Karte auf den ersten Treffer.
+  Future<void> _onSearch(String query) async {
+    final q = query.trim();
+    if (q.isEmpty) return;
+    final messenger = ScaffoldMessenger.of(context);
+    try {
+      final uri = Uri.https('nominatim.openstreetmap.org', '/search', {
+        'format': 'json',
+        'addressdetails': '1',
+        'accept-language': 'en',
+        'limit': '1',
+        'q': q,
+      });
+      final response = await http
+          .get(uri, headers: {'User-Agent': 'dmc_app (Drone Mission Control)'});
+      final results = jsonDecode(response.body) as List;
+      if (results.isEmpty) {
+        messenger.showSnackBar(const SnackBar(content: Text('Location not found')));
+        return;
+      }
+      final first = results.first as Map<String, dynamic>;
+      final lat = double.parse(first['lat'] as String);
+      final lon = double.parse(first['lon'] as String);
+      _mapController.move(LatLng(lat, lon), 15);
+      _handleMoveEnd();
+    } catch (_) {
+      messenger.showSnackBar(const SnackBar(content: Text('Search failed')));
+    }
+  }
+
+  /// Zentriert auf den ersten Wegpunkt (HTML-Demonstrator: homeBtn).
+  void _onHomePressed() {
+    final waypoints = ref.read(currentMissionProvider);
+    if (waypoints.isEmpty) {
+      ScaffoldMessenger.of(context)
+          .showSnackBar(const SnackBar(content: Text('No waypoints yet')));
+      return;
+    }
+    final home = waypoints.first;
+    _mapController.move(LatLng(home.lat, home.lon), 16);
+    _handleMoveEnd();
+  }
+
+  /// Zoomt auf die gesamte Mission (HTML-Demonstrator: fitToWaypoints()).
+  void _onFitPressed() {
+    final waypoints = ref.read(currentMissionProvider);
+    if (waypoints.isEmpty) {
+      ScaffoldMessenger.of(context)
+          .showSnackBar(const SnackBar(content: Text('No waypoints to fit')));
+      return;
+    }
+    final points = [for (final w in waypoints) LatLng(w.lat, w.lon)];
+    _mapController.fitCamera(
+      CameraFit.bounds(
+        bounds: LatLngBounds.fromPoints(points),
+        padding: const EdgeInsets.fromLTRB(50, 50, 50, 140),
+      ),
+    );
+    _handleMoveEnd();
+  }
+
   /// Oeffnet die Wegpunktliste als eigene Vollbild-Route statt als
   /// internen Stack-Overlay, damit sie wirklich alles ueberdeckt -
   /// inklusive der Kopfleiste im AppShell darueber.
@@ -357,6 +422,21 @@ class _PlanScreenState extends ConsumerState<PlanScreen> {
               ),
           ],
         ),
+        Positioned(
+          // Direkt unterhalb der Plan/Fly-Kopfleiste (AppShell/TopModeBar),
+          // dieselbe Hoehe wie der Start der Draeder (top:56) - dort ist
+          // die Kopfleiste garantiert bereits zu Ende.
+          top: 62,
+          left: 0,
+          right: 0,
+          child: Center(
+            child: TopNavBar(
+              onSearch: _onSearch,
+              onHome: _onHomePressed,
+              onFit: _onFitPressed,
+            ),
+          ),
+        ),
         if (_mode == _ReticleMode.editing && targetWaypoint != null)
           Align(
             alignment: Alignment.center,

app/lib/ui/widgets/mission_map.dart

@@ -72,13 +72,38 @@ class MissionMap extends StatelessWidget {
           ],
         ),
         CircleLayer(circles: waypointMarkers),
-        SimpleAttributionWidget(
+        const _CompactAttribution(),
-          alignment: Alignment.bottomLeft,
-          source: const Text('OpenStreetMap contributors'),
-          onTap: () =>
-              launchUrl(Uri.parse('https://www.openstreetmap.org/copyright')),
-        ),
       ],
     );
   }
 }
+
+/// Schlanke Pflicht-Attribution fuer die OSM-Kacheln (Tile Usage Policy) -
+/// bewusst ohne den "flutter_map |"-Praefix von SimpleAttributionWidget und
+/// dezenter gestaltet, damit sie nicht wie ein zweiter Balken ueber der
+/// Bottom-Bar wirkt. Bleibt sichtbar und antippbar, da die Policy sichtbare
+/// Namensnennung verlangt.
+class _CompactAttribution extends StatelessWidget {
+  const _CompactAttribution();
+
+  @override
+  Widget build(BuildContext context) {
+    return SafeArea(
+      child: Align(
+        alignment: Alignment.bottomLeft,
+        child: GestureDetector(
+          onTap: () =>
+              launchUrl(Uri.parse('https://www.openstreetmap.org/copyright')),
+          child: Container(
+            padding: const EdgeInsets.symmetric(horizontal: 5, vertical: 1),
+            color: Colors.white.withValues(alpha: 0.5),
+            child: const Text(
+              '© OpenStreetMap contributors',
+              style: TextStyle(fontSize: 9, color: Colors.black87),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}

app/lib/ui/widgets/top_nav_bar.dart

@@ -0,0 +1,110 @@
+import 'package:flutter/material.dart';
+
+/// Suchleiste + Navigations-Buttons (HTML-Demonstrator: #searchWrap/
+/// #homeBtn/#fitBtn). Rendert unterhalb der Plan/Fly-Kopfleiste statt in
+/// dieselbe Pille eingeschmolzen - TopModeBar liegt im AppShell, eine
+/// Ebene ueber PlanScreen, das den MapController besitzt, den Suche/
+/// Home/Fit tatsaechlich benoetigen. Ein gemeinsamer Riverpod-State fuer
+/// den MapController koennte das spaeter fusionieren.
+class TopNavBar extends StatefulWidget {
+  const TopNavBar({
+    super.key,
+    required this.onSearch,
+    required this.onHome,
+    required this.onFit,
+  });
+
+  final ValueChanged<String> onSearch;
+  final VoidCallback onHome;
+  final VoidCallback onFit;
+
+  @override
+  State<TopNavBar> createState() => _TopNavBarState();
+}
+
+class _TopNavBarState extends State<TopNavBar> {
+  final _controller = TextEditingController();
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  void _submit() {
+    widget.onSearch(_controller.text);
+    FocusScope.of(context).unfocus();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Row(
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        Container(
+          width: 260,
+          height: 38,
+          padding: const EdgeInsets.only(left: 12, right: 4),
+          decoration: BoxDecoration(
+            color: Colors.black.withValues(alpha: 0.68),
+            borderRadius: BorderRadius.circular(19),
+            border: Border.all(color: Colors.white.withValues(alpha: 0.4)),
+          ),
+          child: Row(
+            children: [
+              Expanded(
+                child: TextField(
+                  controller: _controller,
+                  onSubmitted: (_) => _submit(),
+                  textInputAction: TextInputAction.search,
+                  style: const TextStyle(color: Colors.white, fontSize: 14),
+                  decoration: InputDecoration(
+                    isDense: true,
+                    border: InputBorder.none,
+                    hintText: 'Search location',
+                    hintStyle:
+                        TextStyle(color: Colors.white.withValues(alpha: 0.55)),
+                  ),
+                ),
+              ),
+              IconButton(
+                onPressed: _submit,
+                icon: const Icon(Icons.search, color: Colors.white, size: 18),
+                padding: EdgeInsets.zero,
+                constraints: const BoxConstraints(minWidth: 30, minHeight: 30),
+              ),
+            ],
+          ),
+        ),
+        const SizedBox(width: 8),
+        _NavIconButton(icon: Icons.home, onTap: widget.onHome),
+        const SizedBox(width: 8),
+        _NavIconButton(icon: Icons.crop_free, onTap: widget.onFit),
+      ],
+    );
+  }
+}
+
+class _NavIconButton extends StatelessWidget {
+  const _NavIconButton({required this.icon, required this.onTap});
+
+  final IconData icon;
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onTap: onTap,
+      child: Container(
+        width: 38,
+        height: 38,
+        decoration: BoxDecoration(
+          shape: BoxShape.circle,
+          color: Colors.black.withValues(alpha: 0.65),
+          border: Border.all(color: Colors.white.withValues(alpha: 0.4)),
+        ),
+        child: Icon(icon, color: Colors.white, size: 18),
+      ),
+    );
+  }
+}

app/test/widget_test.dart

@@ -11,6 +11,7 @@ import 'package:dmc_app/ui/providers/current_mission_provider.dart';
 import 'package:dmc_app/ui/widgets/full_value_chart.dart';
 import 'package:dmc_app/ui/widgets/halo_menu.dart';
 import 'package:dmc_app/ui/widgets/reticle_button.dart';
+import 'package:dmc_app/ui/widgets/top_nav_bar.dart';
 import 'package:dmc_app/ui/widgets/waypoint_chip.dart';
 import 'package:dmc_app/ui/widgets/waypoint_list_panel.dart';
 
@@ -309,4 +310,46 @@ void main() {
     final waypoints = container.read(currentMissionProvider);
     expect(waypoints.single.speedMs, greaterThan(15));
   });
+
+  testWidgets('TopNavBar zeigt Suchfeld und Home-/Fit-Buttons',
+      (tester) async {
+    await _pumpWithContainer(tester);
+
+    expect(find.byType(TopNavBar), findsOneWidget);
+    expect(find.text('Search location'), findsOneWidget);
+    expect(find.byIcon(Icons.home), findsOneWidget);
+    expect(find.byIcon(Icons.crop_free), findsOneWidget);
+  });
+
+  testWidgets('Home-Button ohne Wegpunkte zeigt Hinweis statt Absturz',
+      (tester) async {
+    await _pumpWithContainer(tester);
+
+    await tester.tap(find.byIcon(Icons.home));
+    await tester.pump();
+
+    expect(find.text('No waypoints yet'), findsOneWidget);
+  });
+
+  testWidgets('Fit-Button ohne Wegpunkte zeigt Hinweis statt Absturz',
+      (tester) async {
+    await _pumpWithContainer(tester);
+
+    await tester.tap(find.byIcon(Icons.crop_free));
+    await tester.pump();
+
+    expect(find.text('No waypoints to fit'), findsOneWidget);
+  });
+
+  testWidgets('Leere Suche loest keinen Netzwerkaufruf/Fehler aus',
+      (tester) async {
+    await _pumpWithContainer(tester);
+
+    await tester.enterText(find.byType(TextField), '');
+    await tester.testTextInput.receiveAction(TextInputAction.search);
+    await tester.pump();
+
+    expect(find.text('Search failed'), findsNothing);
+    expect(find.text('Location not found'), findsNothing);
+  });
 }