authentik: speed up first-time signin (single-screen login, live env tuning, asset caching, outpost+nginx hot path)

Viktor asked to review Authentik and the web tier and make first-time
signin to apps faster. Review found the slowness is screens and round
trips, not server time. Changes:

- values.yaml: the authentik.* Helm values (gunicorn workers, cache
  timeouts, conn_max_age) were silently INERT because existingSecret
  skips chart env rendering — pods ran defaults (2 workers, 300s
  caches, no persistent DB conns). Moved all tuning into
  server.env/worker.env, which actually reaches the pods.
- authentik_provider.tf: adopt the identification stage and pin
  password_stage so username+password render on ONE screen (the
  separate order-20 password binding is deleted via API — authentik
  requires that when embedding). Outpost log_level trace->info and
  1->2 replicas (it is on the hot path of every forward-auth request;
  PG-backed sessions make 2 replicas safe).
- authentik module: /static ingress carve-out with immutable
  Cache-Control (assets are version-fingerprinted but served with no
  max-age — internal split-horizon users got zero caching).
- traefik auth-proxy nginx: upstream keepalive 32 + HTTP/1.1 (was
  opening a fresh TCP connection to the outpost per subrequest) +
  config-checksum annotation so config changes roll the pods.
- docs: authentication.md + authentik-state.md updated; fixed stale
  'postgresql.dbaas has no endpoints' claim in CLAUDE.md/CONTEXT.md
  (it is a live CNPG primary-selector compatibility service).

Done via API in the same change (UI-managed objects): 6 OIDC providers
(Vault, Forgejo, Immich, Headscale, linkwarden, Cloudflare Access)
switched from explicit to implicit consent — all first-party, the
4-weekly consent screen only slowed first-time signin.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CONTEXT.md

@@ -149,7 +149,7 @@ _Avoid_: bare "backup" without saying which copy you mean (a service is "backed
 
 **CNPG** / **pg-cluster**:
 **CNPG** is the CloudNativePG operator; **`pg-cluster`** is the Postgres cluster it manages — the shared Postgres substrate. Backs Tier-1 Terraform state (`pg-cluster-rw.dbaas.svc.cluster.local:5432/terraform_state`) and ~12 application databases, reached through **PgBouncer** (a **critical-path Service**) for connection pooling; app credentials rotate via the `vault-database` ClusterSecretStore.
-_Avoid_: "the database" (many DBs share one cluster); the legacy `postgresql.dbaas` Service (no endpoints — dead); conflating the CNPG operator with the `pg-cluster` it manages.
+_Avoid_: "the database" (many DBs share one cluster); the legacy `postgresql.dbaas` Service for NEW work (it is a live compatibility alias selecting the CNPG primary — authentik's PgBouncer still uses it — but `pg-cluster-rw` is the canonical name); conflating the CNPG operator with the `pg-cluster` it manages.
 
 ### Secrets