feat: enhance task management and timeout configurations in multi-agent chat

- Added new environment variables for controlling task execution limits, including `SURFSENSE_SUBAGENT_INVOKE_TIMEOUT_SECONDS`, `SURFSENSE_TASK_BATCH_CONCURRENCY`, and `SURFSENSE_TASK_BATCH_MAX_SIZE`.
- Updated documentation to reflect new batch processing capabilities for `task` calls, allowing for concurrent execution of multiple subagent tasks.
- Improved error handling and receipt generation for deliverables, ensuring consistent feedback on task status.
- Refactored middleware to incorporate search space ID for better task management.

surfsense_backend/app/services/onedrive/kb_sync_service.py

@@ -96,9 +96,7 @@ class OneDriveKBSyncService:
             else:
                 logger.warning("No LLM configured — using fallback summary")
                 summary_content = f"OneDrive File: {file_name}\n\n{indexable_content}"
-                summary_embedding = await asyncio.to_thread(
-                    embed_text, summary_content
-                )
+                summary_embedding = await asyncio.to_thread(embed_text, summary_content)
 
             chunks = await create_document_chunks(indexable_content)
             now_str = datetime.now().strftime("%Y-%m-%d %H:%M:%S")