feat: perf optimizations

- improved search_knowledgebase_tool
- Added new endpoint to batch-fetch comments for multiple messages, reducing the number of API calls.
- Introduced CommentBatchRequest and CommentBatchResponse schemas for handling batch requests and responses.
- Updated chat_comments_service to validate message existence and permissions before fetching comments.
- Enhanced frontend with useBatchCommentsPreload hook to optimize comment loading for assistant messages.

surfsense_backend/app/schemas/chat_comments.py

@@ -87,6 +87,18 @@ class CommentListResponse(BaseModel):
     total_count: int
 
 
+class CommentBatchRequest(BaseModel):
+    """Request for batch-fetching comments for multiple messages."""
+
+    message_ids: list[int] = Field(..., min_length=1, max_length=200)
+
+
+class CommentBatchResponse(BaseModel):
+    """Batch response keyed by message_id."""
+
+    comments_by_message: dict[int, CommentListResponse]
+
+
 # =============================================================================
 # Mention Schemas
 # =============================================================================