V3-04: live map on the recording screen

Feeds RideMap from watchPointsForTrip/watchSegmentsForTrip via autoDispose.family providers. RecordingEngine stays map-free (enforced by architecture_test.dart). RideMap gained lifecycle-aware tile teardown and follow-mode, both shared with the trip-detail map.

lib/src/ui/components/ride_map.dart

@@ -43,21 +43,62 @@ class RideMap extends StatefulWidget {
     required this.points,
     required this.segments,
     this.height = 320,
+    this.follow = false,
   });
 
   final List<TrackPoint> points;
   final List<Segment> segments;
   final double height;
 
+  /// V3-04: keep the latest point centred while recording. A manual pan/pinch turns
+  /// this off until the widget is rebuilt fresh (e.g. a new ride) — chasing the rider
+  /// back to centre after they deliberately looked elsewhere would be worse than not
+  /// following at all.
+  final bool follow;
+
   @override
   State<RideMap> createState() => _RideMapState();
 }
 
-class _RideMapState extends State<RideMap> {
+class _RideMapState extends State<RideMap> with WidgetsBindingObserver {
   final _controller = MapController();
+  late bool _following = widget.follow;
+
+  /// V3-04: a pocketed phone must cost exactly what it costs today. Backgrounding drops
+  /// the tile layer entirely rather than merely pausing it — flutter_map has no pause
+  /// primitive, and an app resume already triggers a full rebuild anyway.
+  bool _backgrounded = false;
+
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addObserver(this);
+  }
+
+  @override
+  void didUpdateWidget(RideMap old) {
+    super.didUpdateWidget(old);
+    if (!_following || widget.points.isEmpty || _backgrounded) return;
+    final last = widget.points.last;
+    // A manual camera move already exists once the controller has been used; jumping
+    // straight to the latest fix keeps the map from ever being one flush behind.
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (!mounted || !_following) return;
+      _controller.move(ll.LatLng(last.latitude, last.longitude), _controller.camera.zoom);
+    });
+  }
+
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState state) {
+    final backgrounded = state != AppLifecycleState.resumed;
+    if (backgrounded != _backgrounded && mounted) {
+      setState(() => _backgrounded = backgrounded);
+    }
+  }
 
   @override
   void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
     _controller.dispose();
     super.dispose();
   }
@@ -122,15 +163,28 @@ class _RideMapState extends State<RideMap> {
             interactionOptions: const InteractionOptions(
               flags: InteractiveFlag.pinchZoom | InteractiveFlag.drag,
             ),
+            onPositionChanged: !widget.follow
+                ? null
+                : (position, hasGesture) {
+                    // Only a real pan/pinch turns following off -- the programmatic
+                    // moves this widget makes to chase the rider must not cancel
+                    // themselves out.
+                    if (hasGesture && _following) {
+                      setState(() => _following = false);
+                    }
+                  },
           ),
           children: [
-            TileLayer(
-              urlTemplate: 'https://tile.openstreetmap.org/{z}/{x}/{y}.png',
-              userAgentPackageName: tileUserAgent,
-              maxNativeZoom: maxTileZoom.toInt(),
-              // Respect OSM's usage policy: render what is looked at, never bulk prefetch.
-              panBuffer: 0,
-            ),
+            // Omitted entirely while backgrounded -- not just visually hidden -- so no
+            // tile request can fire off-screen. See the lifecycle observer above.
+            if (!_backgrounded)
+              TileLayer(
+                urlTemplate: 'https://tile.openstreetmap.org/{z}/{x}/{y}.png',
+                userAgentPackageName: tileUserAgent,
+                maxNativeZoom: maxTileZoom.toInt(),
+                // Respect OSM's usage policy: render what is looked at, never bulk prefetch.
+                panBuffer: 0,
+              ),
             PolylineLayer(polylines: polylines),
           ],
         ),