Adds the Open WebUI stack at openwebui.basicstack.de:
- Namespace `openwebui`, ArgoCD Application with auto-sync + selfHeal
- Own Postgres 16 + pgvector (`pgvector/pgvector:pg16`, 20Gi encrypted PVC,
fsn1-pinned); VECTOR_DB=pgvector, extension auto-created
- Own Redis 7 (2Gi encrypted PVC, fsn1-pinned) used both as cache and as
websocket manager (db=1)
- Hetzner Object Storage bucket `openwebui-basicstack` (hel1, path-style)
for file uploads; shared project S3 credentials
- Traefik ingress + Let's Encrypt TLS
- Pocket ID client `Open WebUI` (PKCE on) restricted to groups
`openwebui_admins` and `openwebui_users`; `andreas.leinen@basicstack.de`
is member of both and gets admin via OAUTH_ADMIN_ROLES
- Password login disabled (`ENABLE_LOGIN_FORM=false`, `ENABLE_SIGNUP=false`)
Co-Authored-By: Paperclip <noreply@paperclip.ing>
