fix: raise Trendnet motion threshold to reduce dark-frame CPU waste

threshold 30→40, contour_area 10→25. Prevents noisy dark frames
from triggering object detection (49% detect CPU on black image).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: web-flow

gitops/clusters/homelab/apps/frigate/configmap.yaml

@@ -78,8 +78,8 @@ data:
           track:
             - person
         motion:
-          threshold: 30
-          contour_area: 10
+          threshold: 40
+          contour_area: 25
           improve_contrast: true
         record:
           enabled: true