Authentik SSO + homepage naked domain

Auth layer (Authentik 2026.8.0):
- compose: 3-service stack (authentik-postgres, authentik-server, authentik-worker),
  postgres health-gated, bind mounts under /home/dank/authentik
- Caddyfile: auth.franksdank.cloud vhost; forward_auth on the no-auth vhosts
  (homepage, SearXNG, Hermes, Prometheus, RomM, Copyparty); outpost path
  proxied first in a route block
- .env.example: AUTHENTIK_PG_PASS + AUTHENTIK_SECRET_KEY
- deploy.sh: render only CADDY_BASICAUTH_HASH (the homepage per-user hashes
  are retired; grafana + pihole keep basicauth)
- tests/authentik.bats (new) + updated homepage/caddyfile/pihole seams
- docs: Authentik.md + per-service pages; Caddy.md + Homepage.md updated

Homepage (naked domain):
- Caddyfile: dankclaw.franksdank.cloud -> franksdank.cloud www.franksdank.cloud;
  dankclaw + dankserver redirect to it; bare-IP catch-all updated
- addn-hosts: A records for the naked domain, www, and auth (all -> 143)
- tests/pihole.bats: vhost_names handles multi-address blocks; TLD check
  allows the naked domain

All 146 tests pass.

docs/Infrastructure/authentik-server.md

@@ -0,0 +1,15 @@
+# authentik-server
+
+The Authentik server — the core, the admin API, and the embedded Caddy outpost.
+This is the service the Caddy `forward_auth` vhosts proxy to
+(`authentik-server:9000`). It also serves the login page at
+`https://auth.franksdank.cloud`.
+
+- **Compose service:** `authentik-server` (in `dankclaw/compose.yaml`)
+- **Image:** `ghcr.io/goauthentik/server:2026.8.0` (command: `server`)
+- **Port:** `9000` (published; the outpost + admin + login all live here)
+- **Data:** `/home/dank/authentik/data` (bind mount, shared with the worker)
+- **Health:** `http://localhost:9000/-/health/`
+
+See [Authentik.md](Authentik.md) for the full architecture, the Caddy
+forward_auth pattern, first-time setup, and failure modes.