docs: Jellyfin LDAP 401 resolved — legacy /Users/Auth/Password route removed in 12.1

The auth works via the modern /Users/AuthenticateByName endpoint (what the
web UI uses). The 401 was a test artifact from probing the dead legacy route.
No config change needed; LDAP-Auth plugin + authentik 2026.8.3 outpost healthy.

serverAppConfigs-docs/Dankserver/Jellyfin.md

@@ -95,6 +95,15 @@ service-account password is stored only in the Jellyfin plugin config (the
 search both succeed from Dankclaw; a real user (`alex`, in `jellyfin_users`)
 logged into the web UI with their authentik password and the plugin created
 the matching Jellyfin user.
+**Gotcha — the login endpoint changed in Jellyfin 12.1.** The legacy
+`POST /Users/Auth/Password` route (and its `LegacyEmbyRouteRewriteMiddleware`)
+was removed; probing it now returns a silent 401 with no plugin log, which
+reads like an auth failure but is just a dead route. The web UI and modern
+clients use `POST /Users/AuthenticateByName` (with the `Authorization:
+MediaBrowser Client=…, DeviceId=…, Device=…, Version=…` header), which is
+where the LDAP plugin runs. Verified 2026-09-25: `alex` authenticates over
+`AuthenticateByName` (HTTP 200; full plugin flow logged — service bind,
+search, `ldapUid`, user bind, token).
 
 ## Configuration workflow