feat(mobile): mobile-responsive UI — bottom tab bar, bottom-sheet dialogs, PWA

All changes are gated behind max-md:/md:hidden so the >=768px desktop layout is untouched (verified with lint + build + live checks at 375px).

- globals.css: one mobile block — 16px inputs (no iOS auto-zoom), units sidebar stacks above content, wizard item rows become 2-col (text fields full-width, delete button full-width), dd-panels / flow diagram / conv-form stack, larger touch targets
- ui/dialog.tsx: dialogs become full-width bottom sheets on mobile (all modals inherit it); desktop keeps the centered dialog
- Header: sticky on mobile only + PageLayout bottom clearance
- New MobileTabBar: role-aware bottom tabs (office admin/manager, inventory PM, inventory admin); hidden on /wizard
- Wizard step 4: TouchSensor (150ms delay) so touch drag works without stealing scroll
- JalaliDatePicker: dropdown capped to viewport; bigger day cells and time inputs on mobile
- PWA: manifest.webmanifest + 192/512 icons (scripts/gen-pwa-icons.ps1) + theme-color/manifest links in index.html
- New docs/mobile-responsive.md documenting the full change set

frontend/src/App.tsx

@@ -1,6 +1,7 @@
 import { lazy, Suspense } from "react";
 import { Navigate, Route, Routes } from "react-router-dom";
 import { useAuthStore } from "./store/auth";
+import { MobileTabBar } from "./components/layout/MobileTabBar";
 
 // هر صفحه با React.lazy لود می‌شود (code splitting)
 const DashboardPage = lazy(() =>
@@ -65,8 +66,9 @@ function HomeRoute() {
 
 export default function App() {
   return (
-    <Suspense fallback={<Loading />}>
-      <Routes>
+    <>
+      <Suspense fallback={<Loading />}>
+        <Routes>
         <Route path="/login" element={<LoginPage />} />
         <Route
           path="/"
@@ -192,7 +194,9 @@ export default function App() {
           }
         />
         <Route path="*" element={<Navigate to="/" replace />} />
-      </Routes>
-    </Suspense>
+        </Routes>
+      </Suspense>
+      <MobileTabBar />
+    </>
   );
 }