Nav2 导航集成：新增 nav2_navigator.py，mission_executor 改用 Nav2 action 导航

- 新增 agv_app/utils/nav2_navigator.py：Nav2Navigator 类，通过 ros2 action
  /navigate_to_pose 和 /navigate_through_poses 与 Nav2 通信，支持路径点导航
- app.py：navigate/to, navigate/path, navigate/status 三个 API 改用 Nav2Navigator
- mission_executor.py：_execute_point 中调用 _nav2_go_to_point() 替代原来的
  time.sleep 模拟移动，Nav2 负责从当前点到目标点的自主导航
- 原有的 map_navigator.py（A* + Pure Pursuit 自实现）保留不动，供无 Nav2 时降级用

agv_app/app.py

@@ -17,7 +17,7 @@ from utils.agv_controller_ros2 import AGVController
 from utils.qr_scanner import QRScanner
 from utils.image_uploader import ImageUploader
 from utils.mission_executor import MissionExecutor, TaskStatus
-from utils.map_navigator import MapNavigator, NavStatus
+from utils.nav2_navigator import Nav2Navigator, Nav2Status
 
 # 配置日志
 logging.basicConfig(
@@ -51,7 +51,7 @@ class GlobalState:
             "positions": []               # 独立点位配置 [{row, col, side, coords, poses}]
         }
         self.machines_config = []        # 机器配置（每台机器的正面/背面点位+姿态）
-        self.navigator = None              # MapNavigator 实例
+        self.navigator = None              # Nav2Navigator 实例
         self.lock = threading.Lock()
 
     def reset(self):
@@ -412,12 +412,13 @@ def api_navigate_to():
 
     try:
         if gs.navigator is None:
-            gs.navigator = MapNavigator(gs.map_config["map_yaml"])
-        ok = gs.navigator.navigate_to(float(goal_x), float(goal_y))
+            gs.navigator = Nav2Navigator()
+        # navigate_to_pose(x, y, yaw=None, timeout_sec=120, blocking=False)
+        ok = gs.navigator.navigate_to_pose(float(goal_x), float(goal_y), blocking=False)
         if ok:
             return jsonify({"ok": True, "message": "导航已启动"})
         else:
-            return jsonify({"ok": False, "error": "路径规划失败或导航正在进行中"}), 400
+            return jsonify({"ok": False, "error": "导航启动失败，可能是Nav2未运行或AGV未连接"}), 400
     except Exception as e:
         logger.error(f"导航失败: {e}")
         return jsonify({"ok": False, "error": str(e)}), 500
@@ -437,12 +438,12 @@ def api_navigate_status():
     """获取导航状态"""
     if gs.navigator:
         return jsonify(gs.navigator.get_status())
-    return jsonify({"status": "idle", "current_position": [0, 0, 0], "path_length": 0, "path": []})
+    return jsonify({"status": "idle", "current_position": [0, 0, 0], "nav2_available": False})
 
 
 @app.route("/api/navigate/path", methods=["POST"])
 def api_navigate_path():
-    """预览路径（仅规划不执行）"""
+    """预览路径（仅规划不执行）- Nav2版本不支持预计算路径，返回当前导航状态"""
     if not gs.map_config or "map_yaml" not in gs.map_config:
         return jsonify({"ok": False, "error": "地图未加载"}), 400
 
@@ -454,12 +455,16 @@ def api_navigate_path():
 
     try:
         if gs.navigator is None:
-            gs.navigator = MapNavigator(gs.map_config["map_yaml"])
-        path = gs.navigator.get_path_preview(float(goal_x), float(goal_y))
-        if path is not None:
-            return jsonify({"ok": True, "path": path, "length": len(path)})
-        else:
-            return jsonify({"ok": False, "error": "路径规划失败，目标点不可达"}), 400
+            gs.navigator = Nav2Navigator()
+        # Nav2 不提供路径预览，直接返回可用状态
+        current = gs.navigator.get_current_position()
+        status = gs.navigator.get_status()
+        return jsonify({
+            "ok": True,
+            "message": "Nav2 路径预览不可用，请在 RViz 中查看规划路径",
+            "current_position": current,
+            "nav2_available": status.get("nav2_available", False)
+        })
     except Exception as e:
         logger.error(f"路径预览失败: {e}")
         return jsonify({"ok": False, "error": str(e)}), 500