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.

dankclaw/pihole/addn-hosts

@@ -10,10 +10,15 @@
 #   192.168.0.235 = dankserver (media stack; reached by Caddy via published
 #                    LAN ports — no DNS records point here)
 
-# --- Homepage + legacy name ---
+# --- Homepage (naked domain + www) + legacy names ---
+192.168.0.143 franksdank.cloud
+192.168.0.143 www.franksdank.cloud
 192.168.0.143 dankclaw.franksdank.cloud
 192.168.0.143 dankserver.franksdank.cloud
 
+# --- Authentik (SSO / OIDC provider) ---
+192.168.0.143 auth.franksdank.cloud
+
 # --- Media services (dankserver, proxied) ---
 192.168.0.143 plex.franksdank.cloud
 192.168.0.143 plex.franksdank.casa