feat: 重构存储策略为 SQLite

- 新增 config/database.py: SQLite 数据库管理器
  - WAL 模式提升写入性能
  - 异步批量写入队列
  - 滚动清理机制（保留7天）

- 新增 core/storage_manager.py: 图片存储管理
  - 异步保存抓拍图片
  - 本地缓存断网容灾
  - 按日期分目录存储

- 更新 config/settings.py: 添加 SQLite 配置
  - SQLiteConfig 数据类
  - 环境变量支持

- 更新 core/result_reporter.py: 适配新存储
  - 使用 SQLite 替代 MySQL
  - AlertInfo 数据类重构
  - 断网自动缓存到本地

config/settings.py

@@ -10,7 +10,7 @@ from typing import List, Optional
 
 @dataclass
 class DatabaseConfig:
-    """数据库配置类"""
+    """数据库配置类（MySQL - 云端）"""
     host: str = "localhost"
     port: int = 3306
     username: str = "root"
@@ -21,6 +21,17 @@ class DatabaseConfig:
     echo: bool = False
 
 
+@dataclass
+class SQLiteConfig:
+    """SQLite 配置（边缘侧本地存储）"""
+    db_path: str = "./data/security_events.db"
+    image_dir: str = "./data/captures"
+    retention_days: int = 7
+    wal_mode: bool = True
+    batch_size: int = 100
+    flush_interval: float = 5.0
+
+
 @dataclass
 class RedisConfig:
     """Redis配置类"""
@@ -61,7 +72,7 @@ class VideoStreamConfig:
 @dataclass
 class InferenceConfig:
     """推理配置类"""
-    model_path: str = "./models/yolov8s.engine"
+    model_path: str = "./models/yolo11n.engine"
     input_width: int = 480
     input_height: int = 480
     batch_size: int = 1
@@ -111,7 +122,6 @@ class Settings:
     
     def _load_env_vars(self):
         """从环境变量加载配置"""
-        # 数据库配置
         self.database = DatabaseConfig(
             host=os.getenv("DB_HOST", "localhost"),
             port=int(os.getenv("DB_PORT", "3306")),
@@ -120,14 +130,19 @@ class Settings:
             database=os.getenv("DB_DATABASE", "edge_inference"),
         )
         
-        # Redis配置
+        self.sqlite = SQLiteConfig(
+            db_path=os.getenv("SQLITE_DB_PATH", "./data/security_events.db"),
+            image_dir=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",
+        )
+        
         self.redis = RedisConfig(
             host=os.getenv("REDIS_HOST", "localhost"),
             port=int(os.getenv("REDIS_PORT", "6379")),
             password=os.getenv("REDIS_PASSWORD"),
         )
         
-        # MQTT配置
         self.mqtt = MQTTConfig(
             broker_host=os.getenv("MQTT_BROKER_HOST", "localhost"),
             broker_port=int(os.getenv("MQTT_BROKER_PORT", "1883")),
@@ -136,13 +151,11 @@ class Settings:
             password=os.getenv("MQTT_PASSWORD"),
         )
         
-        # 视频流配置
         self.video_stream = VideoStreamConfig(
             default_fps=int(os.getenv("VIDEO_DEFAULT_FPS", "5")),
             reconnect_max_attempts=int(os.getenv("VIDEO_RECONNECT_ATTEMPTS", "5")),
         )
         
-        # 推理配置
         self.inference = InferenceConfig(
             model_path=os.getenv("MODEL_PATH", "./models/yolo11n.engine"),
             input_width=int(os.getenv("INPUT_WIDTH", "480")),
@@ -153,13 +166,11 @@ class Settings:
             nms_threshold=float(os.getenv("NMS_THRESHOLD", "0.45")),
         )
         
-        # 日志配置
         self.log_level = os.getenv("LOG_LEVEL", "INFO")
         self.log_dir = os.getenv("LOG_DIR", "./logs")
-        self.log_file_max_size = int(os.getenv("LOG_FILE_MAX_SIZE", "10485760"))  # 10MB
+        self.log_file_max_size = int(os.getenv("LOG_FILE_MAX_SIZE", "10485760"))
         self.log_file_backup_count = int(os.getenv("LOG_FILE_BACKUP_COUNT", "5"))
         
-        # 工作时间配置
         self.working_hours = self._parse_working_hours()
     
     def _parse_working_hours(self) -> List[dict]: