## Summary
- Adds SSO-Auth.xml, LDAP-Auth.xml, and branding.xml plugin config (rendered by an initContainer into /config) to fafflix and cheeztv
- Adds a per-namespace oauth-credentials VaultStaticSecret to each instance
- Adds a "Sign in with SSO" login link via jellyfin branding config
## Why
Phase-1 jellyfin auth: browser SSO via the 9p4 SSO plugin (Authentik OIDC, ak_groups claim) and phone/TV app-passwords via the LDAP plugin against the Authentik LDAP outpost. Config is declarative — restarts overwrite UI edits. Activates when the plugin-baked jellyfin-ha image lands (separate PR).
Reviewed-on: #424
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>
