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/components/ui/dialog.tsx

@@ -33,12 +33,14 @@ const DialogContent = React.forwardRef<
       ref={ref}
       className={cn(
         "fixed left-1/2 top-1/2 z-50 grid max-h-[90vh] w-full max-w-lg -translate-x-1/2 -translate-y-1/2 gap-4 overflow-y-auto rounded-xl border border-line bg-panel p-6 shadow-lg",
+        // موبایل: دیالوگ به‌جای وسط، bottom-sheet تمام‌عرض می‌شود (دسکتاپ بی‌تغییر)
+        "max-md:inset-x-0 max-md:bottom-0 max-md:top-auto max-md:max-h-[85dvh] max-md:max-w-none max-md:translate-x-0 max-md:translate-y-0 max-md:rounded-b-none max-md:rounded-t-2xl max-md:p-4 max-md:pb-[calc(env(safe-area-inset-bottom)+0.75rem)]",
         className,
       )}
       {...props}
     >
       {children}
-      <DialogPrimitive.Close className="absolute end-4 top-4 rounded-sm opacity-70 transition-opacity hover:opacity-100 focus:outline-none focus:ring-2 focus:ring-accent/40">
+      <DialogPrimitive.Close className="absolute end-4 top-4 rounded-sm opacity-70 transition-opacity hover:opacity-100 focus:outline-none focus:ring-2 focus:ring-accent/40 max-md:p-1.5">
         <X className="h-4 w-4" />
         <span className="sr-only">بستن</span>
       </DialogPrimitive.Close>