docs(caddy): put both auth walls in the guard-a-new-vhost procedure

Step 1 gains the closing sentence the abs-proxy incident demands: the ak-shell
snippet that creates a ProxyProvider with objects.create() must be followed by
scripts/authentik-proxy-provider-defaults.sh, or the guard fails before any
credential. Step 2 gains the forwarded-scheme clause for any app that derives its
own origin from the request. Each fact keeps one owner — the laws stay on
[[Authentik Outpost Reference]] (provisioning rule 3) and [[Audiobookshelf]]; this
page only says where in the procedure they bite. Outpost page timestamp bumped to
match its substantive edit.

serverAppConfigs-docs/Infrastructure/Authentik Outpost Reference.md

@@ -4,7 +4,7 @@ description: "Outpost, proxy-provider, OAuth2, LDAP and flow configuration for t
 tags:
   - infrastructure
   - authentik
-timestamp: 2026-10-19
+timestamp: 2026-11-03
 ---
 
 # Authentik Outpost Reference

serverAppConfigs-docs/Infrastructure/Caddy.md

@@ -125,10 +125,24 @@ authentik's error page instead of the app.
    outpost routes on the ORIGINAL `Host` header alone, so anything else matches zero
    providers. Never print a provider's fields wholesale — a proxy provider carries a
    client secret, and it lands in whatever transcript the command runs in.
+
+   `ProxyProvider.objects.create()` is not the API: the serializer's
+   `set_oauth_defaults()` never runs, so the row lands with `redirect_uris` and
+   `grant_types` empty, and the guard fails *before* any credential — authentik's
+   "Redirect URI Error" page, then a bodiless HTTP 400 once the URIs are filled
+   by hand. Run `scripts/authentik-proxy-provider-defaults.sh` after the snippet
+   (idempotent, covers every provider; `--check` is the census); law and failure
+   signatures in [[Authentik Outpost Reference]].
 2. **Then the route.** The public site block proxies the whole request to `anubis:8923`
    with `header_up X-Real-Ip {remote_host}`, and the post-auth `http://:8017` listener
    gains a `@<name> host <vhost>` handler pointing at the app — copy `romm`/`files`,
    which are the same shape including a Dankserver LAN-port upstream.
+   An app that derives its own origin from the request needs the scheme pinned:
+   Audiobookshelf checks every OIDC callback against `x-forwarded-proto://Host`; this
+   listener is fed over plain http so Caddy's own `X-Forwarded-Proto` is `http`, and the
+   app answers a 400 "Invalid callback URL - must be same-origin" for its own https
+   callback. The edge for a guarded name is TLS-only, so `header_up X-Forwarded-Proto
+   https` is the truthful value ([[Audiobookshelf]]).
 3. **Then the name and the audit.** A `dankclaw/pihole/addn-hosts` line (the `pihole`
    seam fails the build if a Caddyfile vhost has no record), a Porkbun A record if the
    name must resolve off-LAN ([[LAN-DNS]]), and the subdomain added to `GUARDED` in