feat(security): digest-pin every registry image on all three hosts (fleet law)

Closing the command-center security queue #70/#71/#72/#73/#74: rolling tags
let a rebuild move under a running service with nobody approving it, and
make a CVE audit ungradeable. 36 quadlet units across dankclaw, dankserver
and frankbook-pro now carry tag@sha256; localhost/* builds stay exempt
(their build is the pin). The pihole and copyparty pins pull the fixed
builds; valkey 9.1.2 (already running) and redis 7.4.11 are pinned in
place, vendor fixes TBD.

New gate tests/quadlet_image_pins.bats: no unpinned registry image, no
generator-rejected key anywhere. Three seams that pinned the old exact-tag
law (frankbook readarr, open_webui, seerr) now require tag AND digest -
strictly stronger. Quadlet Lifecycle docs: batch-abort law, entrypoint
flags-only law, pin law.

serverAppConfigs-docs/Architecture/Quadlet Lifecycle.md

@@ -130,10 +130,19 @@ Quickest unblock: `podman compose up -d --force-recreate <svc>`. Durable fix
 
 ## 4. Podman 5.x quadlet v1 generator quirks (verified live 2026-08-28)
 
-- **Hard-fail keys** — the whole unit silently fails to generate
-  (`systemctl --user cat <unit>` shows "could not be found"): any
-  dash-prefixed `[Container]` option (`--shm-size=…` → `unsupported key …
-  in group 'Container'`); `Command=` is unsupported, use `Exec=`.
+- **Hard-fail keys abort the WHOLE BATCH, not one unit** (podman 5.7.0,
+  live 2026-10-21): one unsupported key — e.g. `HostAddr=` — makes the
+  generator log `unsupported key … in group 'Container'` plus
+  `processing encountered some errors` and generate NOTHING for that
+  manager. The running containers keep going as orphans, so the failure
+  first appears on the next deploy as `Unit <x>.service not found` for a
+  service that is visibly up. Other offenders: any dash-prefixed
+  `[Container]` option (`--shm-size=…`), `Command=` (use `Exec=`).
+  The seam `tests/quadlet_image_pins.bats` fails the build on any
+  generator-rejected key in any host's units.
+  Also: an image whose ENTRYPOINT is the binary takes FLAGS ONLY in
+  `Exec=` — repeating the binary makes it a positional arg
+  (`unexpected /bin/blackbox_exporter`, live 2026-10-21).
 - **HealthCmd space-splitting:** the v1 generator splits `HealthCmd` on
   spaces into the healthcheck argv; a quoted probe
   `/bin/sh -c "pg_isready …"` lands as argv token `"pg_isready` →
@@ -148,6 +157,16 @@ Quickest unblock: `podman compose up -d --force-recreate <svc>`. Durable fix
   "unsupported key"`, `systemctl --user cat probe.service` (shows the
   generated ExecStart verbatim), then remove + reload.
 
+## 4a. Image pins (fleet law, 2026-10-21)
+
+Every registry image in a quadlet is digest-pinned (`tag@sha256:…`);
+locally built images (`localhost/*`, `franksdank/*`) are exempt — their
+build is the pin. A rolling tag lets a rebuild move under a running
+service with nobody approving it, and it makes a CVE audit ungradeable.
+Gate: `tests/quadlet_image_pins.bats`. Where upstream publishes no version
+tags (copyparty-ac stops at 1.19.15), pin `:latest@sha256:` and name the
+version the config label carries in the comment beside it.
+
 ## 5. Rootless Quadlet log retrieval
 
 Step 0 — establish ownership: `systemctl --user status <name>.service`