feat(pos): clickable POS v2 redesign prototype at /pos2 (static, no backend)

Responsive RTL big-touch reimagining of the POS order screen for judging the
redesign on real devices before decomposing the 1568-line pos-screen.tsx + wiring
real logic. Self-contained: mock menu + local cart, no API/store/SignalR.

- 3 zones: category chips + item grid · order ticket · sticky action bar.
- lg+ side-panel ticket; smaller screens get a "view order" bar + slide-over
  (covers landscape tablet, portrait tablet, phone).
- Big-touch (56px primary / 44px qty), brand green #0F6E56, Toman totals.
  Send/Pay are mock toasts. tsc clean.

web/dashboard/src/app/[locale]/(fullscreen)/pos2/page.tsx

@@ -0,0 +1,7 @@
+import { Pos2Prototype } from "@/components/pos2/pos2-prototype";
+
+/** POS v2 — clickable static prototype (mock data, no backend). Open at /<locale>/pos2
+ *  on a tablet/phone to judge the redesigned layout before we decompose + wire it. */
+export default function Pos2PrototypePage() {
+  return <Pos2Prototype />;
+}