feat(profile): implement user-initiated GDPR-compliant profile deletion

- Add DELETE /users/me endpoint with cascading data removal
- Implement frontend confirmation dialog and deletion flow
- Add audit logging for deletion requests
- Update localization files for new UI strings
- Add scheduled cleanup service for AI traces
- Document GDPR compliance in technical specification

BREAKING CHANGE: Users can now permanently delete their profiles and associated data

flutter/lib/features/profile/data/profile_repository.dart

@@ -42,6 +42,14 @@ class ProfileRepository {
     return UserProfile.fromJson(data);
   }
 
+  Future<void> deleteMe() async {
+    final token = await _ref.read(authStateProvider.future);
+    await guardedApiCall(
+      _ref,
+      () => _apiClient.deleteJson(UserApiPaths.me, token: token),
+    );
+  }
+
   Future<void> refreshCategories() async {
     final token = await _ref.read(authStateProvider.future);
     await guardedApiCall(