V3-07: route drawing (pins and straight lines)

Route plans are their own entity (RoutePlan/Waypoint, schema v3), never joined into ride totals or the rides list. RoutePlanRepository recomputes straight-line distance after every waypoint mutation. RoutePlannerScreen supports tap-to-add, tap-to-delete, and hand-rolled drag-to-move via MapCamera's screen/latlng conversions.

Fixed a real bug found by testing: FlutterMap's initialCenter/initialZoom are read once at construction, so building the map before the waypoints stream's first emission froze the camera on null-island. Also documents a genuine ten-minute test hang traced to Stream.first on a Drift watch() query inside testWidgets, which needs a pump-driven Timer that flutter_test's fake zone never advances on its own.

test/migration_test.dart

@@ -147,4 +147,34 @@ void main() {
     expect(all.length, 3);
     expect(all.every((t) => t.activity == Activity.motorcycle), isTrue);
   });
+
+  test('a v2 database (V3-07) gains route_plans/waypoints and keeps its trips',
+      () async {
+    // v2: identical to the v1 seed above, plus the `activity` column V3-01 added.
+    seedV1Database();
+    final raw = sqlite3.sqlite3.open(dbFile.path);
+    raw.execute('''
+      ALTER TABLE trips ADD COLUMN activity TEXT NOT NULL DEFAULT 'motorcycle';
+    ''');
+    raw.execute('PRAGMA user_version = 2;');
+    raw.close();
+
+    final db = AppDatabase(NativeDatabase(dbFile));
+    addTearDown(db.close);
+
+    // The pre-existing ride is untouched by an upgrade that has nothing to do with it.
+    final trip = await db.getTrip(1);
+    expect(trip, isNotNull);
+    expect(trip!.name, 'Old ride');
+
+    // The new tables are not just present but usable.
+    final routeId = await db.insertRoutePlan(
+      const RoutePlan(name: 'Coast loop', createdAt: 9000),
+    );
+    await db.insertWaypoint(
+      Waypoint(routeId: routeId, ordinal: 0, latitude: 51.0, longitude: -114.0),
+    );
+    final waypoints = await db.waypointsForRoute(routeId);
+    expect(waypoints, hasLength(1));
+  });
 }