refactor: serve.py 改用 starlette + uvicorn，统一支持 HTTP/WebSocket/API 代理

install.sh

@@ -100,10 +100,8 @@ cd "$FRONTEND_DIR"
 npm install
 npm run build
 
-# 安装前端 Python 依赖 (serve.py 需要 websockets)
-if ! pip show websockets &>/dev/null; then
-    pip install -r requirements.txt
-fi
+# 安装前端 Python 依赖 (starlette + uvicorn)
+pip install -r requirements.txt
 
 echo -e "${YELLOW}[5/5] 验证前端...${NC}"
 if [[ -d "dist" ]]; then