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/(dashboard)/admin/usuarios/page.tsx

@@ -173,7 +173,7 @@ export default function AdminUsuariosPage() {
                   onChange={(e) => setSearchTerm(e.target.value)}
                 />
               </div>
-              <div className="w-[250px]">
+              <div className="w-full sm:w-[250px]">
                 <Select value={filterTenant} onValueChange={setFilterTenant}>
                   <SelectTrigger>
                     <SelectValue placeholder="Filtrar por empresa" />
@@ -337,7 +337,7 @@ export default function AdminUsuariosPage() {
                                     value={editingUser.role}
                                     onValueChange={(v) => setEditingUser({ ...editingUser, role: v as any })}
                                   >
-                                    <SelectTrigger className="h-8 w-[140px]">
+                                    <SelectTrigger className="h-8 w-full sm:w-[140px]">
                                       <SelectValue />
                                     </SelectTrigger>
                                     <SelectContent>