fix(psa): use board/id in (...) for multi-board filter per CW docs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/services/psa/connectwise/provider.py

@@ -84,8 +84,8 @@ class ConnectWiseProvider(PSAProvider):
             conditions.append("resources = null")
         board_ids: list[int] = filters.get("board_ids") or []
         if board_ids:
-            board_cond = " or ".join(f"board/id = {bid}" for bid in board_ids)
-            conditions.append(f"({board_cond})")
+            board_list = ", ".join(str(bid) for bid in board_ids)
+            conditions.append(f"board/id in ({board_list})")
 
         if conditions:
             params["conditions"] = " and ".join(conditions)