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

app/utils/env_utils.py

@@ -0,0 +1,54 @@
+import logging
+import os
+
+logger = logging.getLogger(__name__)
+
+
+def update_env_file(settings_to_update: dict[str, str]) -> bool:
+    """
+    Updates the .env file with the given settings (best-effort).
+    Creates or modifies existing keys.
+
+    Args:
+        settings_to_update: A dictionary mapping uppercase env var names to their new string values.
+
+    Returns:
+        True if the file was successfully updated, False otherwise.
+    """
+    try:
+        env_path = os.path.join(os.path.dirname(os.path.dirname(os.path.dirname(__file__))), ".env")
+        if not os.path.exists(env_path):
+            logger.warning(f".env file not found at {env_path}, skipping file write")
+            return False
+
+        logger.info(f"Updating settings in {env_path}")
+
+        with open(env_path, "r") as f:
+            env_lines = f.readlines()
+
+        updated = set()
+        new_env_lines = []
+        for line in env_lines:
+            stripped_line = line.rstrip()
+            is_updated = False
+            for key, value in settings_to_update.items():
+                if stripped_line.startswith(f"{key}=") or stripped_line.startswith(f"# {key}="):
+                    new_env_lines.append(f"{key}={value}")
+                    updated.add(key)
+                    is_updated = True
+                    break
+            if not is_updated:
+                new_env_lines.append(stripped_line)
+
+        for key, value in settings_to_update.items():
+            if key not in updated:
+                new_env_lines.append(f"{key}={value}")
+
+        with open(env_path, "w") as f:
+            f.write("\n".join(new_env_lines) + "\n")
+
+        logger.info("Successfully updated settings in .env file")
+        return True
+    except Exception as env_err:
+        logger.warning(f"Failed to write .env file (non-fatal): {env_err}")
+        return False