chore(devices): TEMP power_telemetry at error level to flush fingers_crossed

Prod monolog wraps the main handler in fingers_crossed(action_level: error),
so info-level logs sit in a 50-message buffer and get discarded at request
end. That's why three deploy+bounce cycles produced zero power_telemetry
lines in docker logs despite the unconditional log call. Logging at error
level forces the buffer to flush to php://stderr → docker logs. Will be
demoted when the surrounding TEMP block is removed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/Controller/DeviceImageController.php

@@ -96,7 +96,13 @@ class DeviceImageController extends AbstractController
         // controller filtering them out. Greppable via
         // `device.poll.power_telemetry`. Remove alongside the firmware's
         // NVS_KEY_PREV_* writes once validated.
-        $this->logger->info('device.poll.power_telemetry', [
+        // TEMP: logged at error level (not info) so monolog's prod
+        // fingers_crossed handler flushes it to stderr → docker logs.
+        // INFO sits in a 50-message buffer that only flushes on a real
+        // error within the same request, so info-level diagnostic lines
+        // never reach the log stream. Demote when the surrounding TEMP
+        // block is removed.
+        $this->logger->error('device.poll.power_telemetry', [
             'mac'                => $mac,
             'prev_awake_ms'      => $request->headers->get('X-Prev-Awake-Ms'),
             'prev_panel_init_ms' => $request->headers->get('X-Prev-Panel-Init-Ms'),