Unify header pill/button height to 38px, matching the HTML prototype

Measured the prototype screenshot pixel-for-pixel: content pills take
up ~79% of the header's total height, matching its own CSS
(height:38px, topBarWrap padding:5px 10px -> 48px total). The Flutter
port had drifted to 34px for HeaderWindPill, MapSearchControls, and
NavIconButton, while FlightModePill was left at the original 38px -
so Fly mode looked inconsistent against itself, and both modes wasted
more header height as margin than the prototype does. Bringing all
four back to a shared 38px fixes both.

app/lib/ui/widgets/map_search_controls.dart

@@ -89,11 +89,14 @@ class _MapSearchControlsState extends ConsumerState<MapSearchControls> {
       children: [
         Expanded(
           child: Container(
-            height: 34,
+            // 38 statt vorher 34, deckungsgleich mit HeaderWindPill/
+            // FlightModePill/NavIconButton (Nutzerwunsch: einheitliche
+            // Kopfleisten-Hoehe wie im HTML-Demonstrator vermessen).
+            height: 38,
             padding: const EdgeInsets.only(left: 12, right: 4),
             decoration: BoxDecoration(
               color: Colors.black.withValues(alpha: 0.55),
-              borderRadius: BorderRadius.circular(17),
+              borderRadius: BorderRadius.circular(19),
             ),
             child: Row(
               children: [