fix: merge main, resolve conflicts, address review feedback

- Resolve merge conflicts in app/api/onedrive.py and tests/test_api_google_drive_final.py
- Fix legacy Dict[str, str] type hints in update_env_file functions to use dict[str, str]
- Add admin-only access (_require_admin dependency) to save-settings endpoints
  in google_drive.py, onedrive.py, and dropbox.py
- Fix in_memory_only response field to reflect actual env_write_success status
- Update tests to override _require_admin dependency for save-settings endpoint tests

tests/test_wizard_db_persist.py

@@ -129,6 +129,15 @@ class TestSetupWizardUndoSkip:
 class TestDropboxSaveSettingsDbPersist:
     """Unit tests for save_dropbox_settings DB persistence."""
 
+    @pytest.fixture(autouse=True)
+    def _admin_override(self):
+        from app.api.dropbox import _require_admin
+        from app.main import app as fastapi_app
+
+        fastapi_app.dependency_overrides[_require_admin] = lambda: {"is_admin": True}
+        yield
+        fastapi_app.dependency_overrides.pop(_require_admin, None)
+
     @patch("app.api.dropbox.settings")
     @patch("app.api.dropbox.notify_settings_updated")
     @patch("app.api.dropbox.save_setting_to_db")
@@ -268,6 +277,15 @@ class TestGoogleDriveUpdateSettingsDbPersist:
 class TestOneDriveSaveSettingsDbPersist:
     """Unit tests for save_onedrive_settings DB persistence."""
 
+    @pytest.fixture(autouse=True)
+    def _admin_override(self):
+        from app.api.onedrive import _require_admin
+        from app.main import app as fastapi_app
+
+        fastapi_app.dependency_overrides[_require_admin] = lambda: {"is_admin": True}
+        yield
+        fastapi_app.dependency_overrides.pop(_require_admin, None)
+
     @patch("app.api.onedrive.settings")
     @patch("app.api.onedrive.notify_settings_updated")
     @patch("app.api.onedrive.save_setting_to_db")