fix(spoolbuddy): lower /update permission to INVENTORY_UPDATE so kiosk's own Settings -> Update button works

The kiosk's Settings -> Update Daemon button returned "API keys cannot
  be used for administrative operations" because POST /spoolbuddy/devices/
  {id}/update was gated on Permission.SETTINGS_UPDATE, and SETTINGS_UPDATE
  is in the _APIKEY_DENIED_PERMISSIONS deny-list introduced by PR #1241.
  Every kiosk-side request tripped the deny-list before the API key's
  scope set (Read / Print Queue / Control / Legacy) was even consulted.

  Same root cause as the four QuickMenu System buttons fixed in 0.2.4b3
  (Restart Daemon / Restart Browser / Reboot / Shutdown). Missed /update
  in that audit on the reasoning "replaces the daemon binary, different
  threat surface" — but that's wrong: restart_daemon already replaces
  the running daemon process, so daemon-replacement is not a step up in
  blast radius. The SSH update is also strictly scoped to the one device
  the operator physically controls (git fetch + pip install + systemctl
  restart on that host) — same threat profile as the system commands
  already running on INVENTORY_UPDATE.

  Lower /spoolbuddy/devices/{id}/update from SETTINGS_UPDATE to
  INVENTORY_UPDATE so it aligns with the rest of the kiosk-scoped routes
  (calibration/tare, display, cancel-write, system/command,
  system/command-result, update-status). The main Bambuddy in-app updater
  at POST /api/v1/updates/apply keeps SETTINGS_UPDATE — that one runs on
  the Bambuddy host and is correctly fenced behind the deny-list.

backend/app/api/routes/spoolbuddy.py

@@ -1319,7 +1319,14 @@ async def trigger_daemon_update(
     device_id: str,
     req: dict | None = None,
     db: AsyncSession = Depends(get_db),
-    _: User | None = RequirePermissionIfAuthEnabled(Permission.SETTINGS_UPDATE),
+    # Aligns with the rest of the kiosk-scoped device routes (calibration,
+    # display, cancel-write, system/command — all INVENTORY_UPDATE).
+    # SETTINGS_UPDATE is on the API-key deny-list, which blocks the Update
+    # button from the kiosk's own Settings page even when the operator has
+    # physical access. Update only acts on the device the operator already
+    # controls (git fetch + pip install + systemctl restart on that one
+    # host) — same blast radius as the restart_daemon command.
+    _: User | None = RequirePermissionIfAuthEnabled(Permission.INVENTORY_UPDATE),
 ):
     """Trigger a SpoolBuddy update over SSH.