chore: refactor and cleanup of system services

lib/firebase/options.dart

@@ -0,0 +1,8 @@
+import 'package:firebase_core/firebase_core.dart' show FirebaseOptions;
+
+/// Stub that allows building the application but with Firebase disabled.
+class DefaultFirebaseOptions {
+  static FirebaseOptions get currentPlatform {
+    throw UnsupportedError('Firebase is not supported on this platform.');
+  }
+}