refactor(statistic): decouple statistics collection from report generation

Introduces a dedicated `HTMLReportGenerator` class in `report_generator.py` to handle all aspects of HTML and chart rendering. This decouples the report presentation logic from the data collection process within `StatisticOutputTask`.

Key changes include:
- Migrated all HTML and JavaScript generation into the new `HTMLReportGenerator`.
- Extracted all statistic key constants into a separate `statistic_keys.py` file for improved organization.
- Renamed `_generate_chart_data` to `_collect_chart_data` to better reflect its purpose.
- Improved data handling robustness by using `.get()` for dictionary access and safely handling database query results.

src/manager/local_store_manager.py

@@ -21,6 +21,10 @@ class LocalStoreManager:
         self.store = {}
         self.load_local_store()
 
+    def __contains__(self, key: str) -> bool:
+        """检查键是否存在"""
+        return key in self.store
+
     def __getitem__(self, item: str) -> str | list | dict | int | float | bool | None:
         """获取本地存储数据"""
         return self.store.get(item)
@@ -38,9 +42,9 @@ class LocalStoreManager:
         else:
             logger.warning(f"尝试删除不存在的键: {key}")
 
-    def __contains__(self, item: str) -> bool:
-        """检查本地存储数据是否存在"""
-        return item in self.store
+    def get(self, key: str, default=None):
+        """获取本地存储数据，支持默认值"""
+        return self.store.get(key, default)
 
     def load_local_store(self):
         """加载本地存储数据"""