Refactor contacts management and improve path handling

- Updated ContactsProvider to initialize with device public key for filtering out self contacts.
- Added methods to check if a contact has a learned routing path and to get path quality indicators.
- Enhanced AppProvider to initialize ContactsProvider with device public key.
- Modified ConnectionProvider to log path status when sending messages.
- Created ContactStorageService for persisting contacts to local storage.
- Removed import/export functionality from MapManagementScreen.
- Updated UI components in DirectMessageSheet and SarUpdateSheet to use theme colors.
- Removed file_picker dependency from pubspec.yaml and generated plugin registrant.

pubspec.lock

@@ -129,14 +129,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "7.0.1"
-  file_picker:
-    dependency: "direct main"
-    description:
-      name: file_picker
-      sha256: ab13ae8ef5580a411c458d6207b6774a6c237d77ac37011b13994879f68a8810
-      url: "https://pub.dev"
-    source: hosted
-    version: "8.3.7"
   fixnum:
     dependency: transitive
     description:
@@ -270,14 +262,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "10.1.1"
-  flutter_plugin_android_lifecycle:
-    dependency: transitive
-    description:
-      name: flutter_plugin_android_lifecycle
-      sha256: c2fe1001710127dfa7da89977a08d591398370d099aacdaa6d44da7eb14b8476
-      url: "https://pub.dev"
-    source: hosted
-    version: "2.0.31"
   flutter_test:
     dependency: "direct dev"
     description: flutter