feat: add signal trap and graceful shutdown to dev.sh

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

backend/dev.sh

@@ -7,6 +7,32 @@
 
 set -e
 
+# 信号捕获：优雅退出
+cleanup() {
+    echo ""
+    echo -e "${YELLOW}🛑 收到停止信号，正在关闭所有服务...${NC}"
+
+    # 先杀所有 watcher 和 debounce 进程（防止继续触发重启）
+    if [ -f /tmp/dev_sh_watchers.tmp ]; then
+        while read watcher_pid; do
+            kill "$watcher_pid" 2>/dev/null || true
+        done < /tmp/dev_sh_watchers.tmp
+        rm -f /tmp/dev_sh_watchers.tmp
+    fi
+
+    # 清理所有 PID 文件并杀服务进程
+    for service in activityService galleryService socialService assetService userService gateway; do
+        pkill -9 -f "$service" 2>/dev/null || true
+        rm -f "/tmp/dev_sh_${service}.pid" "/tmp/dev_sh_${service}_restart"
+        echo -e "${YELLOW}  🛑 $service 已停止${NC}"
+    done
+
+    echo -e "${GREEN}✅ 所有服务已关闭${NC}"
+    exit 0
+}
+
+trap cleanup SIGINT SIGTERM
+
 RED='\033[0;31m'
 GREEN='\033[0;32m'
 YELLOW='\033[1;33m'