file structure and initial map_data scaffold

lib/services/map_data.dart

@@ -0,0 +1,29 @@
+import 'dart:typed_data';
+import 'package:latlong2/latlong.dart';
+import 'package:flutter_map/flutter_map.dart' show LatLngBounds;
+import '../models/osm_camera_node.dart';
+
+/// Central provider for map tiles and camera data, abstracting local/disk and remote/OSM fetches.
+class MapDataProvider {
+  static final MapDataProvider _instance = MapDataProvider._();
+  factory MapDataProvider() => _instance;
+  MapDataProvider._();
+
+  /// Returns tile bytes for this tile, or null if unavailable (when [allowRemote] is false and not found offline)
+  /// [preferLocal]: try disk cache first
+  /// [allowRemote]: if true, will request OSM server if tile not on disk and not in offline mode
+  Future<Uint8List?> getTile(int z, int x, int y,
+      {bool preferLocal = true, bool allowRemote = true}) async {
+    // Scaffold: real logic will go here
+    throw UnimplementedError('getTile needs implementation');
+  }
+
+  /// Returns camera nodes for a given bounding box.
+  /// [preferLocal]: try disk cache first
+  /// [allowRemote]: query Overpass if true (and allowed by offline mode)
+  Future<List<OsmCameraNode>> getCameras(LatLngBounds bounds,
+      {bool preferLocal = false, bool allowRemote = true}) async {
+    // Scaffold: real logic will go here
+    throw UnimplementedError('getCameras needs implementation');
+  }
+}