Add a new `refresh_user_cache` method to `DataAccessLayer` that re-caches user objects by both ID and username with the configured TTL. Update `basic_auth` and `webdav_auth` handlers to call this method after successful authentication, ensuring the enterprise cache stays synchronized with user lookups from the fallback ORM path.
Implement JWT token decoding from cookies as a secondary authentication method in webdav_auth, falling back to Basic Auth then session cookie. Add full test suite (735 lines) covering OPTIONS, PROPFIND, and authorization scenarios for WebDAV endpoints.
