Refactor core service dependencies

[jjoonleo]

Summary

• inject TokenInterceptor token/session collaborators through AppDio instead of resolving them with getIt
• delegate NotificationService FCM token registration and tap routing through explicit seams
• add concrete FCM registration and navigation tap router tests

Tests

• dart run build_runner build --delete-conflicting-outputs
• flutter test test/core/dio/interceptors/token_interceptor_test.dart test/core/dio/transformers/logging_transformer_test.dart test/core/services/notification_service_test.dart test/core/services/notification_tap_router_test.dart test/data/services/device_fcm_token_registrar_test.dart test/core/services/fallback_alarm_notification_service_test.dart
• flutter analyze
• flutter test

Closes #528