feat(ui): make dashboard responsive for iPhone and mobile devices

- Add Sheet primitive component for mobile drawers
- Add MobileNav with hamburger menu for dashboard layout
- Hide desktop sidebars on mobile; show mobile header
- Make dashboard header responsive with stacked layout on small screens
- Hide selector text on mobile, show icons only
- Convert fixed-width filters to responsive widths (CFDI, Clientes, Admin, Documentos, Alertas)
- Cap dialog widths to 95vw on mobile (CFDI viewer, Documentos, Reportes, Contribuyentes, Facturación)
- Make calendar grid smaller and use single-letter weekdays on mobile
- Update viewport to include viewport-fit=cover for Samsung safe areas

apps/web/app/layout.tsx

@@ -1,4 +1,4 @@
-import type { Metadata } from 'next';
+import type { Metadata, Viewport } from 'next';
 import { Inter } from 'next/font/google';
 import './globals.css';
 import { ThemeProvider } from '@/components/providers/theme-provider';
@@ -11,6 +11,12 @@ export const metadata: Metadata = {
   description: 'Plataforma de análisis financiero y gestión fiscal para empresas mexicanas',
 };
 
+export const viewport: Viewport = {
+  width: 'device-width',
+  initialScale: 1,
+  viewportFit: 'cover',
+};
+
 export default function RootLayout({
   children,
 }: {