feat: 单智能体模式下加载用户所有知识库

- get_bot_settings 接口中，单智能体模式时加载用户的所有知识库
- 不再从 settings_json 读取 dataset_ids

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

routes/bot_manager.py

@@ -1508,12 +1508,24 @@ async def get_bot_settings(bot_uuid: str, authorization: Optional[str] = Header(
                     api_key=None
                 )
 
-            # 处理 dataset_ids：将字符串转换为数组
-            dataset_ids = settings.get('dataset_ids')
-            if dataset_ids and isinstance(dataset_ids, str):
-                dataset_ids = [id.strip() for id in dataset_ids.split(',') if id.strip()]
-            elif not dataset_ids:
-                dataset_ids = None
+            # 处理 dataset_ids
+            # 单智能体模式：加载用户的所有知识库
+            # 普通模式：从 settings 读取
+            if SINGLE_AGENT_MODE:
+                await cursor.execute("""
+                    SELECT dataset_id
+                    FROM user_datasets
+                    WHERE user_id = %s
+                    ORDER BY created_at DESC
+                """, (user_id,))
+                user_datasets = await cursor.fetchall()
+                dataset_ids = [row[0] for row in user_datasets] if user_datasets else []
+            else:
+                dataset_ids = settings.get('dataset_ids')
+                if dataset_ids and isinstance(dataset_ids, str):
+                    dataset_ids = [id.strip() for id in dataset_ids.split(',') if id.strip()]
+                elif not dataset_ids:
+                    dataset_ids = None
 
             return BotSettingsResponse(
                 bot_id=str(bot_id),