Lock app to landscape fullscreen and add first OSM map

- Lock orientation to landscape (sensorLandscape in the manifest,
  SystemChrome.setPreferredOrientations in main.dart) and enable immersive
  fullscreen, matching the prototype's full-bleed map UI (doc 7.7).
- Add MissionMap widget: flutter_map + standard OSM raster tiles, same
  default center/zoom as the HTML prototype (Amsterdam, zoom 16), OSM
  attribution bottom-left. PlanScreen now renders it full-screen instead of
  the placeholder text.
- Add the release-manifest INTERNET permission (previously only present in
  the debug manifest, which would have silently broken tile loading and any
  future network calls in release builds).
- Update the smoke test to check for the FlutterMap widget instead of the
  removed placeholder text.

Verified with flutter analyze, flutter test, and a real run on the
Pixel_10a emulator (fullscreen landscape confirmed, tiles loading).

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

app/pubspec.lock

@@ -917,6 +917,70 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.9"
+  url_launcher:
+    dependency: "direct main"
+    description:
+      name: url_launcher
+      sha256: f6a7e5c4835bb4e3026a04793a4199ca2d14c739ec378fdfe23fc8075d0439f8
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.2"
+  url_launcher_android:
+    dependency: transitive
+    description:
+      name: url_launcher_android
+      sha256: b413d49b73867ac08dd2f9890efd3cc11f2a0e577618d50843440a1fb3776c32
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.32"
+  url_launcher_ios:
+    dependency: transitive
+    description:
+      name: url_launcher_ios
+      sha256: "580fe5dfb51671ae38191d316e027f6b76272b026370708c2d898799750a02b0"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.4.1"
+  url_launcher_linux:
+    dependency: transitive
+    description:
+      name: url_launcher_linux
+      sha256: d5e14138b3bc193a0f63c10a53c94b91d399df0512b1f29b94a043db7482384a
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.2.2"
+  url_launcher_macos:
+    dependency: transitive
+    description:
+      name: url_launcher_macos
+      sha256: "368adf46f71ad3c21b8f06614adb38346f193f3a59ba8fe9a2fd74133070ba18"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.2.5"
+  url_launcher_platform_interface:
+    dependency: transitive
+    description:
+      name: url_launcher_platform_interface
+      sha256: "552f8a1e663569be95a8190206a38187b531910283c3e982193e4f2733f01029"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.2"
+  url_launcher_web:
+    dependency: transitive
+    description:
+      name: url_launcher_web
+      sha256: "85c81589622fbc87c1c683aaea164d3604a7777495a79d91e39ffcdec39ddb34"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.3"
+  url_launcher_windows:
+    dependency: transitive
+    description:
+      name: url_launcher_windows
+      sha256: "712c70ab1b99744ff066053cbe3e80c73332b38d46e5e945c98689b2e66fc15f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.5"
   uuid:
     dependency: transitive
     description:
@@ -1015,4 +1079,4 @@ packages:
     version: "3.1.3"
 sdks:
   dart: ">=3.12.2 <4.0.0"
-  flutter: ">=3.38.4"
+  flutter: ">=3.44.0"