fix(hitl): rollback on KB delete failure, tighten linear tool guards

- delete_linear_issue + delete_notion_page: add db_session.rollback()
  in the KB document deletion exception handler so the session is never
  left in a PendingRollbackError state after a failed commit, which
  would otherwise break all subsequent DB operations in the same request
- delete_linear_issue: include issue identifier (e.g. ENG-42) in the
  success message so the caller can confirm which issue was archived
- update_linear_issue: remove redundant label_ids ternary
  (x if x is not None else None -> x)
- create_linear_issue: add logger.error on empty-title guard for parity
  with the equivalent Notion tool

surfsense_backend/app/agents/new_chat/tools/notion/delete_page.py

@@ -240,8 +240,7 @@ def create_delete_notion_page_tool(
                         logger.warning(f"Document {document_id} not found in KB")
                 except Exception as e:
                     logger.error(f"Failed to delete document from KB: {e}")
-                    # Don't fail the whole operation if KB deletion fails
-                    # The page is already deleted from Notion, so inform the user
+                    await db_session.rollback()
                     result["warning"] = (
                         f"Page deleted from Notion, but failed to remove from knowledge base: {e!s}"
                     )