fix(webui): enforce full-result DataGrid queries

docs/UI_UX_DECISION_LEDGER.md

@@ -233,6 +233,12 @@ instead of reproducing their behavior.
   `disabledReason` for row state; omit an action only when that action does not
   belong to the table. `minimumSlots` reserves trailing positions for an empty
   row. `DataGridEmptyAction` does this for the standard add/move/remove layout.
+- A paginated `DataGrid` has exactly one query owner. Client mode receives the
+  complete logical row set and applies filtering and sorting before slicing a
+  page. Server mode receives only the loaded page, requires `onQueryChange`,
+  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.
 - Feedback and confirmation use `Dialog`, `ConfirmDialog`, or
   `DismissibleAlert`. They never fall back to `window.alert`.