fix: menu item/category create, demo banner reach, token refresh, blog publish

Dashboard & API bug fixes for owner-reported breakage:

- MenuController validators (PosValidators): NameEn was required but the
  dashboard sends null when blank, so every manual menu-item create failed
  and category create failed 100% (the form never sends nameEn). Now optional.
- DemoDataBanner: only showed when a cafe was exactly empty, so
  showcase-seeded cafes (2-3 cats / 3-5 items) could never trigger the
  one-click seed. Widened gate to sparse menus (<5 cats && <10 items) and
  added a clear "nothing to add" message when already populated.
- client.ts: added one-time JWT refresh-and-retry on 401 (shared in-flight
  promise) before bouncing to /login. Expired access tokens silently broke
  ticket list, add-table, and other reads.
- Surface API errors as toasts on menu + table mutations (were swallowed
  silently, so failures looked like "nothing happens").
- Admin blog editor: saving an edit dropped IsPublished (defaulted false,
  silently unpublishing the post on every save); now persisted with a
  toggle. Also hoisted the inner Field component to module scope - it was
  remounting every input on each keystroke and dropping focus.
- Admin integrations: replaced raw radio gateway selector with a styled
  RadioDot matching the iOS toggles.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/dashboard/src/components/tables/tables-screen.tsx

@@ -123,7 +123,9 @@ export function TablesScreen() {
       refresh();
     },
     onError: (err) => {
-      setActionMessage(err instanceof ApiClientError ? err.message : t("createError"));
+      const msg = err instanceof ApiClientError ? err.message : t("createError");
+      setActionMessage(msg);
+      notify.error(msg);
     },
   });
 
@@ -185,6 +187,11 @@ export function TablesScreen() {
       setActionMessage(null);
       refresh();
     },
+    onError: (err) => {
+      const msg = err instanceof ApiClientError ? err.message : t("createError");
+      setActionMessage(msg);
+      notify.error(msg);
+    },
   });
 
   const startEdit = (table: TableBoardItem) => {