add google_fonts dependency, implement feature inspection on map, and enhance tile cache management

lib/pages/map/vector/mapbox_vector_tile_cache.dart

@@ -68,4 +68,9 @@ class MapboxVectorTileCache {
       _cache.remove(_cache.keys.first);
     }
   }
+
+  static void clear() {
+    _cache.clear();
+    _inFlight.clear();
+  }
 }

lib/pages/map/vector/tile_pyramid_cache.dart

@@ -17,18 +17,13 @@ class _TileCoord {
 }
 
 class CachedTile {
-  CachedTile(this.image, this.zoomBucket);
+  CachedTile(this.image);
 
   final ui.Image image;
-  final int zoomBucket;
 }
 
-// Static tile pyramid image cache. Stores rasterised ui.Image per (z, x, y).
-// Each entry also records the zoom bucket it was rendered at — callers can
-// check whether a re-render is warranted, but the old image stays as a
-// fallback until the new one arrives.
-//
-// Ancestor lookup (for fallback blitting) just calls peek() at a coarser z.
+// Static tile pyramid image cache. Stores one rasterised ui.Image per
+// deterministic pyramid tile coordinate (z, x, y).
 class TilePyramidCache {
   TilePyramidCache._();
 
@@ -67,7 +62,6 @@ class TilePyramidCache {
     int z,
     int x,
     int y,
-    int zoomBucket,
     Future<ui.Image?> Function() render,
     void Function() onReady,
   ) {
@@ -77,14 +71,7 @@ class TilePyramidCache {
     if (filter != null && !filter(z, x, y)) return;
     _inFlight.add(coord);
 
-    _queue.add(
-      _Queued(
-        coord: coord,
-        zoomBucket: zoomBucket,
-        render: render,
-        onReady: onReady,
-      ),
-    );
+    _queue.add(_Queued(coord: coord, render: render, onReady: onReady));
     _drain();
   }
 
@@ -118,7 +105,7 @@ class TilePyramidCache {
         existing.image.dispose();
       }
 
-      _cache[item.coord] = CachedTile(image, item.zoomBucket);
+      _cache[item.coord] = CachedTile(image);
       _approxBytes += _estimateBytes(image);
       _trim();
 
@@ -176,13 +163,11 @@ class TilePyramidCache {
 class _Queued {
   const _Queued({
     required this.coord,
-    required this.zoomBucket,
     required this.render,
     required this.onReady,
   });
 
   final _TileCoord coord;
-  final int zoomBucket;
   final Future<ui.Image?> Function() render;
   final void Function() onReady;
 }