feat(aiot): 告警冷却时间调整 + 截图本地保留 + 中文路径修复

- 离岗检测冷却时间: 300s → 600s（10分钟）
- 入侵检测冷却时间: 120s → 300s（5分钟）
- 入侵告警级别改为高（alarm_level=3）
- COS 不可用时保留本地截图文件，不再上报后删除
- 修复 cv2.imwrite 中文路径失败，改用 imencode + write_bytes
- 配置订阅在 LOCAL 模式下跳过 Redis 连接

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

config/settings.py

@@ -92,7 +92,7 @@ class COSConfig:
 @dataclass
 class AlarmUploadConfig:
     """告警上报配置"""
-    cloud_api_url: str = "http://124.221.55.225:8000"
+    cloud_api_url: str = "http://localhost:8000"
     edge_token: str = ""
     retry_max: int = 3
     retry_interval: int = 5
@@ -123,6 +123,18 @@ class InferenceConfig:
     fp16_mode: bool = True
 
 
+# ===================== Debug / Local Sync =====================
+
+@dataclass
+class DebugConfig:
+    """本地调试相关配置"""
+    enabled: bool = True
+    host: str = "127.0.0.1"
+    port: int = 9001
+    reload_signal_file: str = "./config/reload.signal"
+    local_config_path: str = "./config/local_config.json"
+
+
 # COCO 数据集类别名称（YOLO 模型使用）
 COCO_CLASS_NAMES = [
     "person", "bicycle", "car", "motorcycle", "airplane", "bus", "train", "truck", "boat",
@@ -177,6 +189,20 @@ class Settings:
     
     def _load_env_vars(self):
         """从环境变量加载配置"""
+        # 加载 .env 文件（如果 python-dotenv 可用）
+        try:
+            from dotenv import load_dotenv
+            load_dotenv()
+        except ImportError:
+            pass
+
+        base_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+
+        def _abs_path(path: str) -> str:
+            if not path:
+                return path
+            return path if os.path.isabs(path) else os.path.normpath(os.path.join(base_dir, path))
+
         self.database = DatabaseConfig(
             host=os.getenv("DB_HOST", "localhost"),
             port=int(os.getenv("DB_PORT", "3306")),
@@ -186,8 +212,8 @@ class Settings:
         )
         
         self.sqlite = SQLiteConfig(
-            db_path=os.getenv("SQLITE_DB_PATH", "./data/security_events.db"),
-            image_dir=os.getenv("SQLITE_IMAGE_DIR", "./data/captures"),
+            db_path=_abs_path(os.getenv("SQLITE_DB_PATH", "./data/security_events.db")),
+            image_dir=_abs_path(os.getenv("SQLITE_IMAGE_DIR", "./data/captures")),
             retention_days=int(os.getenv("SQLITE_RETENTION_DAYS", "7")),
             wal_mode=os.getenv("SQLITE_WAL_MODE", "1") == "1",
         )
@@ -229,11 +255,13 @@ class Settings:
         )
 
         self.alarm_upload = AlarmUploadConfig(
-            cloud_api_url=os.getenv("CLOUD_API_URL", "http://124.221.55.225:8000"),
+            cloud_api_url=os.getenv("CLOUD_API_URL", "http://localhost:8000"),
             edge_token=os.getenv("EDGE_TOKEN", ""),
             retry_max=int(os.getenv("ALARM_RETRY_MAX", "3")),
             retry_interval=int(os.getenv("ALARM_RETRY_INTERVAL", "5")),
         )
+
+        self.alarm_upload_enabled = os.getenv("ALARM_UPLOAD_ENABLED", "1") == "1"
         
         self.video_stream = VideoStreamConfig(
             default_fps=int(os.getenv("VIDEO_DEFAULT_FPS", "5")),
@@ -248,6 +276,16 @@ class Settings:
             conf_threshold=float(os.getenv("CONF_THRESHOLD", "0.5")),
             nms_threshold=float(os.getenv("NMS_THRESHOLD", "0.45")),
         )
+
+        self.config_sync_mode = os.getenv("CONFIG_SYNC_MODE", "LOCAL").upper()
+
+        self.debug = DebugConfig(
+            enabled=os.getenv("DEBUG_SERVER_ENABLED", "1") == "1",
+            host=os.getenv("DEBUG_SERVER_HOST", "127.0.0.1"),
+            port=int(os.getenv("DEBUG_SERVER_PORT", "9001")),
+            reload_signal_file=_abs_path(os.getenv("DEBUG_RELOAD_SIGNAL_FILE", "./config/reload.signal")),
+            local_config_path=_abs_path(os.getenv("LOCAL_CONFIG_PATH", "./config/local_config.json")),
+        )
         
         self.log_level = os.getenv("LOG_LEVEL", "INFO")
         self.log_dir = os.getenv("LOG_DIR", "./logs")