- Added 401-handling response interceptor to sidecar axios instance
(matches existing http instance) so expired/invalid tokens redirect
to login instead of showing raw 404/401 errors
- Added GET /api/sidecar/folders — proxies PhotoPrism's
/api/v1/folders/originals with BasePath post-filter
- Updated listFolders() frontend to call sidecar proxy
- Updated plan with remaining fixes
