Task #16: Per-user drag-and-drop reorder for Home apps

- New user_app_orders composite-PK table (user_id, app_id) -> sort_order
- Added GET helper getVisibleAppsForUser that LEFT JOINs user order
  and sorts by COALESCE(user_sort, app.sort_order, name)
- New PUT /api/me/app-order endpoint validates payload, filters to
  visible apps, dedupes, replaces row set in a transaction
- Frontend: wrapped home apps grid in @dnd-kit DndContext + SortableContext
  with PointerSensor (distance:8) and TouchSensor (delay:250 / tolerance:5)
  so taps still navigate while a press-and-drag reorders
- Optimistic local state with rollback on error; useEffect skips sync
  while a save mutation is in flight to avoid stomping on user changes
- Bottom dock intentionally NOT sortable (per user choice)
- DB schema pushed manually via SQL (drizzle-kit push prompted for
  rename ambiguity); regenerated api-zod / api-client-react
- Verified end-to-end: PUT /api/me/app-order returns reordered list
  and subsequent GET /api/apps reflects the new per-user order

artifacts/teaboy-os/src/pages/home.tsx

@@ -98,8 +98,8 @@ export default function HomePage() {
   const [orderedApps, setOrderedApps] = useState<App[] | null>(null);
 
   useEffect(() => {
-    if (apps && !updateOrder.isPending) setOrderedApps(apps);
-  }, [apps, updateOrder.isPending]);
+    if (apps) setOrderedApps((prev) => prev ?? apps);
+  }, [apps]);
 
   const sensors = useSensors(
     useSensor(PointerSensor, { activationConstraint: { distance: 8 } }),
@@ -112,12 +112,18 @@ export default function HomePage() {
     const oldIndex = orderedApps.findIndex((a) => a.id === active.id);
     const newIndex = orderedApps.findIndex((a) => a.id === over.id);
     if (oldIndex < 0 || newIndex < 0) return;
+    const previous = orderedApps;
     const next = arrayMove(orderedApps, oldIndex, newIndex);
     setOrderedApps(next);
     updateOrder.mutate(
       { data: { order: next.map((a) => a.id) } },
       {
+        onSuccess: (data) => {
+          setOrderedApps(data);
+          queryClient.setQueryData(getListAppsQueryKey(), data);
+        },
         onError: () => {
+          setOrderedApps(previous);
           queryClient.invalidateQueries({ queryKey: getListAppsQueryKey() });
         },
       },