Implement mobile route editor with MapLibre and BRouter routing

Route editing (Phase 3.3):
- useRouteEditor hook: waypoint state, add/move/delete, BRouter
  routing via Journal API proxy, GPX generation, save to API
- RouteMap component: MapLibre Native with OSM raster tiles,
  route polyline (ShapeSource + LineLayer), waypoint markers
  (MarkerView), long-press to add waypoints, computing indicator
- WaypointSheet: bottom sheet for waypoint actions — delete with
  confirmation, overnight stop toggle, coordinates display
- Route detail screen: view mode (map preview + stats) and edit
  mode (full-screen map with save button)
- Unsaved changes guard on navigation (beforeRemove listener)
- Smart waypoint insertion at nearest route segment
- Waypoint extraction from GPX via regex (sync, no DOM needed)

Adds DOM.Iterable to mobile tsconfig for gpx package compat.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/mobile/tsconfig.json

@@ -2,6 +2,7 @@
   "extends": "expo/tsconfig.base",
   "compilerOptions": {
     "strict": true,
-    "allowImportingTsExtensions": true
+    "allowImportingTsExtensions": true,
+    "lib": ["DOM", "DOM.Iterable", "ESNext"]
   }
 }