docs(agents): a start-only quadlet handler no-ops an image bump

The law today's authentik bump paid for: start on an active unit is a no-op, so
the new digest installs and the old container keeps serving behind three green
gates. Restart applies a pin.

AGENTS.md

@@ -741,6 +741,13 @@ linked runbooks.
   `/etc/default/grub`. It replaced `amd_iommu=off`, and the local A/B on byte-identical traffic
   says identity mode costs nothing, so the XDNA2 NPU returned for free.
   [[dankclaw-iommu-translation-off]]
+- **A deploy handler that only `start`s a quadlet no-ops an image bump.**
+  `systemctl --user start` on an already-active unit does nothing, so installing
+  a new digest under a running service keeps the OLD container serving while the
+  deploy, its health gate and the Playwright suite all pass — the authentik
+  handler did exactly that on 2026-10-30 (2026.8.3 → 2026.8.5 moved only the
+  outpost, the one handler that restarted). A pin change is applied by
+  `restart`, never `start`.
 - **Rootless Quadlet containers run with `--replace --rm`**: `podman logs` covers only the CURRENT
   instance; history across recreations lives in `journalctl --user -u <name>.service`. Read
   rootless storage WITHOUT sudo — it is per-user storage, so `sudo podman logs` finds nothing.