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>

server/download_model.sh

@@ -0,0 +1,55 @@
+#!/bin/bash
+# Download MobileNet V2 SSD (COCO, INT8 quantized) for TFLite
+#
+# Model: ssd_mobilenet_v2_coco_quant_postprocess.tflite (~6MB)
+# Source: TensorFlow Model Zoo
+# Classes: 80 COCO object classes
+#
+# This script is idempotent - skips download if model exists.
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+MODEL_DIR="${SCRIPT_DIR}/models"
+MODEL_FILE="${MODEL_DIR}/ssd_mobilenet_v2_coco_quant_postprocess.tflite"
+ZIP_URL="https://storage.googleapis.com/download.tensorflow.org/models/tflite/coco_ssd_mobilenet_v2_quantized_300x300_uint8_20200430.zip"
+ZIP_FILE="${MODEL_DIR}/model.zip"
+
+mkdir -p "${MODEL_DIR}"
+
+if [ -f "${MODEL_FILE}" ]; then
+    echo "Model already exists: ${MODEL_FILE}"
+    echo "Size: $(du -h "${MODEL_FILE}" | cut -f1)"
+    exit 0
+fi
+
+echo "Downloading MobileNet V2 SSD (quantized)..."
+curl -L -o "${ZIP_FILE}" "${ZIP_URL}"
+
+echo "Extracting model..."
+unzip -o "${ZIP_FILE}" -d "${MODEL_DIR}"
+
+# Clean up zip and extra files
+rm -f "${ZIP_FILE}"
+rm -f "${MODEL_DIR}/labelmap.txt"  # We use our own coco_labels.txt
+
+if [ -f "${MODEL_FILE}" ]; then
+    echo "Model downloaded: ${MODEL_FILE}"
+    echo "Size: $(du -h "${MODEL_FILE}" | cut -f1)"
+else
+    # The zip might extract with a slightly different path
+    FOUND=$(find "${MODEL_DIR}" -name "*.tflite" -type f | head -1)
+    if [ -n "${FOUND}" ] && [ "${FOUND}" != "${MODEL_FILE}" ]; then
+        mv "${FOUND}" "${MODEL_FILE}"
+        echo "Model downloaded: ${MODEL_FILE}"
+        echo "Size: $(du -h "${MODEL_FILE}" | cut -f1)"
+    else
+        echo "ERROR: Model file not found after extraction"
+        exit 1
+    fi
+fi
+
+# Clean up any extracted subdirectories
+find "${MODEL_DIR}" -mindepth 1 -type d -exec rm -rf {} + 2>/dev/null || true
+
+echo "Done!"