fix(statistic): 修复统计任务中因数据库记录格式问题导致的异常

在处理来自数据库的记录时，增加对记录类型的检查和时间戳格式的转换。确保即使记录不是预期的字典格式，或者时间戳字段为None或字符串格式，程序也能够安全处理，避免因`TypeError`或`AttributeError`导致整个统计任务中断(说真的这都一天了为什么还没人修)

src/chat/utils/statistic.py

@@ -372,10 +372,19 @@ class StatisticOutputTask(AsyncTask):
             model_class=LLMUsage,
             filters={"timestamp": {"$gte": query_start_time}},
             order_by="-timestamp"
-        )
+        ) or []
         
         for record in records:
-            record_timestamp = record['timestamp']  # 从字典中获取
+            if not isinstance(record, dict):
+                continue
+            
+            record_timestamp = record.get('timestamp')
+            if isinstance(record_timestamp, str):
+                record_timestamp = datetime.fromisoformat(record_timestamp)
+            
+            if not record_timestamp:
+                continue
+
             for idx, (_, period_start) in enumerate(collect_period):
                 if record_timestamp >= period_start:
                     for period_key, _ in collect_period[idx:]:
@@ -420,7 +429,7 @@ class StatisticOutputTask(AsyncTask):
                         stats[period_key][COST_BY_MODULE][module_name] += cost
                         
                         # 收集time_cost数据
-                        time_cost = record.time_cost or 0.0
+                        time_cost = record.get('time_cost') or 0.0
                         if time_cost > 0:  # 只记录有效的time_cost
                             stats[period_key][TIME_COST_BY_TYPE][request_type].append(time_cost)
                             stats[period_key][TIME_COST_BY_USER][user_id].append(time_cost)
@@ -478,11 +487,22 @@ class StatisticOutputTask(AsyncTask):
             model_class=OnlineTime,
             filters={"end_timestamp": {"$gte": query_start_time}},
             order_by="-end_timestamp"
-        )
+        ) or []
         
         for record in records:
-            record_end_timestamp = record['end_timestamp']
-            record_start_timestamp = record['start_timestamp']
+            if not isinstance(record, dict):
+                continue
+
+            record_end_timestamp = record.get('end_timestamp')
+            if isinstance(record_end_timestamp, str):
+                record_end_timestamp = datetime.fromisoformat(record_end_timestamp)
+
+            record_start_timestamp = record.get('start_timestamp')
+            if isinstance(record_start_timestamp, str):
+                record_start_timestamp = datetime.fromisoformat(record_start_timestamp)
+
+            if not record_end_timestamp or not record_start_timestamp:
+                continue
 
             for idx, (_, period_boundary_start) in enumerate(collect_period):
                 if record_end_timestamp >= period_boundary_start:
@@ -523,10 +543,15 @@ class StatisticOutputTask(AsyncTask):
             model_class=Messages,
             filters={"time": {"$gte": query_start_timestamp}},
             order_by="-time"
-        )
+        ) or []
         
         for message in records:
-            message_time_ts = message['time']  # This is a float timestamp
+            if not isinstance(message, dict):
+                continue
+            message_time_ts = message.get('time')  # This is a float timestamp
+
+            if not message_time_ts:
+                continue
 
             chat_id = None
             chat_name = None