Add TFLite object detection to reduce false positives

Motion detection now optionally runs MobileNet V2 SSD (COCO, quantized)
on frames that trigger motion, identifying objects like people, cats, and
cars. Events without detected objects are suppressed by default. Snapshots
include bounding box annotations. New MCP tool vision_get_detections()
enables label-based queries.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -31,3 +31,6 @@ Thumbs.db
 .pytest_cache/
 .coverage
 htmlcov/
+
+# ML model binaries (downloaded during setup)
+*.tflite