feat: Implement background location tracking service

- Removed existing app icons from the asset catalog.
- Added new `Contents.json` for asset catalog.
- Updated `Info.plist` to include background modes and task scheduler identifiers.
- Exposed BLE service in `ConnectionProvider` for background tracking.
- Enhanced `MapTab` to support background location tracking with new service.
- Added `BackgroundLocationService` to manage location updates in the background.
- Updated `SettingsScreen` to allow users to configure GPS update distance and toggle background tracking.
- Implemented functionality to send location updates via BLE in `MeshCoreBleService`.
- Updated dependencies in `pubspec.yaml` for background service support.
- Adjusted `TileCacheService` to ensure ObjectBox is initialized only once.

pubspec.lock

@@ -50,7 +50,7 @@ packages:
     source: hosted
     version: "1.1.2"
   collection:
-    dependency: "direct main"
+    dependency: transitive
     description:
       name: collection
       sha256: "2f5709ae4d3d59dd8f7cd309b4e023046b57d8a6c82130785d2b0e5868084e76"
@@ -158,6 +158,38 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_background_service:
+    dependency: "direct main"
+    description:
+      name: flutter_background_service
+      sha256: "70a1c185b1fa1a44f8f14ecd6c86f6e50366e3562f00b2fa5a54df39b3324d3d"
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.1.0"
+  flutter_background_service_android:
+    dependency: transitive
+    description:
+      name: flutter_background_service_android
+      sha256: ca0793d4cd19f1e194a130918401a3d0b1076c81236f7273458ae96987944a87
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.1"
+  flutter_background_service_ios:
+    dependency: transitive
+    description:
+      name: flutter_background_service_ios
+      sha256: "6037ffd45c4d019dab0975c7feb1d31012dd697e25edc05505a4a9b0c7dc9fba"
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.0.3"
+  flutter_background_service_platform_interface:
+    dependency: transitive
+    description:
+      name: flutter_background_service_platform_interface
+      sha256: ca74aa95789a8304f4d3f57f07ba404faa86bed6e415f83e8edea6ad8b904a41
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.1.2"
   flutter_blue_plus:
     dependency: "direct main"
     description:
@@ -345,7 +377,7 @@ packages:
     source: hosted
     version: "4.1.2"
   intl:
-    dependency: "direct main"
+    dependency: transitive
     description:
       name: intl
       sha256: "3df61194eb431efc39c4ceba583b95633a403f46c9fd341e550ce0bfa50e9aa5"