feat(open-notebook): put the podcast generator behind the guard chain

The service came up internal-only: UI on the LAN at 8502, API at 5056, both
published on every interface, with only its own shared password in front. That
put the episode library outside the fleet's auth chain and one port scan away
from anything on the network.

- Caddy: guarded vhost notebook.franksdank.cloud (Anubis -> Authentik; provider
  notebook-proxy, internal_host caddy:8017) plus the post-auth route to the
  published UI port. One upstream is enough, because the image's own Next.js
  layer rewrites /api/* to the FastAPI beside it — so the API needs no outward
  face at all, and 5056 moves to loopback, where only the deployer's health gate
  dials it.
- scripts/open-notebook.env: API_URL and CORS_ORIGINS become the single guarded
  origin. Left to itself the app auto-detects <host>:5055, the port seerr holds
  on this host; a LAN-origin API_URL would also take the browser around the
  guard chain, where its authenticated session does not ride.
- addn-hosts: the LAN A record. The homepage card goes live and links the vhost.
- Seam: the API origin is derived from whatever the Caddyfile routes to 8502, so
  renaming the vhost moves the test instead of leaving it blessing a stale name,
  and a new test proves the vhost hands the WHOLE request to Anubis.

dankclaw/open-notebook/quadlet/open-notebook.container

@@ -33,17 +33,21 @@
 # and 5055 is exactly the port seerr already holds on this host
 # (`PublishPort=127.0.0.1:5055:5055`; `ss -ltn` on Dankclaw 2026-10-18 shows
 # 127.0.0.1:5055 taken). So the API leaves the container on host port 5056.
-# That forces one setting: the frontend auto-detects the API as
-# `<host-you-opened>:5055`, so API_URL in scripts/open-notebook.env must name
-# the remapped port explicitly, or the UI loads and every call fails. Both
-# ports are published on all interfaces because the consumer is a browser on
-# the LAN — the fleet's browser-facing services (open-webui, comfyui, gitea)
-# bind the same way, while loopback-only is reserved for services whose user
-# path is the guard chain. This service has NO vhost and no Caddy route: it is
-# internal-only until it is guarded, and its own password
-# (OPEN_NOTEBOOK_PASSWORD) is what stands in front of it. That password is not
-# decoration: with it unset the API answers everyone on the LAN, including the
-# unauthenticated episode-audio download.
+# Only 8502 is published on all interfaces, because it is the single upstream
+# the guard chain dials: notebook.franksdank.cloud → anubis → authentik →
+# http://:8017 → 192.168.0.143:8502 (dankclaw/Caddyfile), and this Caddy lives
+# in root's storage, so a published port is the only way it can reach a rootless
+# quadlet. The API needs no outward face at all — the image's own Next.js layer
+# rewrites /api/* to the FastAPI beside it, so one origin serves UI and API —
+# and the fleet's rule is that loopback-only is for services whose user path is
+# the guard chain, which this became on 2026-10-19; 5056 stays published on
+# loopback because the deployer's health gate dials it there. That is also why
+# API_URL in scripts/open-notebook.env names the vhost rather than a port: left
+# to itself the frontend auto-detects `<host-you-opened>:5055`, and the UI loads
+# while every call fails. OPEN_NOTEBOOK_PASSWORD is not made redundant by the
+# chain: it is what keeps the API honest for everything else on this host, and
+# with it unset the API answers anyone, including the unauthenticated
+# episode-audio download.
 #
 # VOLUMES. `/app/data` is a named volume: uploads, the LangGraph SQLite
 # checkpoints and the extraction caches the image keeps under it
@@ -81,7 +85,7 @@ Pull=never
 Network=dankclaw_default
 Network=open-notebook.network
 PublishPort=0.0.0.0:8502:8502
-PublishPort=0.0.0.0:5056:5055
+PublishPort=127.0.0.1:5056:5055
 EnvironmentFile=/home/dank/serverAppConfigs/scripts/open-notebook.env
 EnvironmentFile=/home/dank/Containers/open-notebook/env
 Volume=open-notebook-data:/app/data