Every user — including the initial admin — now gets their own
subdirectory under PHOTO_DIRS (e.g. /photos/admin, /photos/bob).
No one's source root points to the mount root itself, eliminating
cross-user photo overlap entirely.
- Setup endpoint: admin gets /photos/{username} like everyone else
- Migration: default admin media_path set to /photos/admin
- Remove scan directory pruning (no longer needed)
- Fix thumbnail retry URL: use & separator when token query param
already present (was producing ?token=...?retry=N)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>