feat(webui): synchronize external DataGrid queries

docs/UI_UX_DECISION_LEDGER.md

@@ -239,6 +239,9 @@ instead of reproducing their behavior.
   and the backend applies every emitted filter/sort before pagination while
   returning `totalRows` for the filtered result. Server list filters declare
   their complete option domain instead of deriving it from the loaded page.
+  External filter affordances such as summary-count shortcuts update the
+  grid's `query` contract; the grid header controls and backend query therefore
+  always display and execute the same filter state.
 - Feedback and confirmation use `Dialog`, `ConfirmDialog`, or
   `DismissibleAlert`. They never fall back to `window.alert`.