Fix mobile responsiveness across all pages

- PosPage: rooms list becomes horizontal scroll row on mobile instead of w-56 sidebar
- AvailabilityPage: edit panel stacks below grid on mobile (was fixed w-80 side panel)
- UsersPage roles tab: sidebar stacks above permissions on mobile
- All page containers: p-6 → p-4 md:p-6 (TariffsPage, DiscountsPage, MaintenancePage, ReportsPage, DynamicPricingPage, GuestsPage, LoyaltyPage)
- Stats grids: lg:grid-cols-4 → md:grid-cols-4 (GuestsPage, TariffsPage, DiscountsPage, MaintenancePage, ReportsPage, LoyaltyPage)
- Modal form grids: grid-cols-3 → grid-cols-1 sm:grid-cols-3, grid-cols-5 → grid-cols-3 sm:grid-cols-5, grid-cols-4 → grid-cols-2 sm:grid-cols-4
- PosPage modals: fixed w-80/w-96 → responsive w-[calc(100vw-2rem)] sm:w-80/96

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pages/UsersPage.tsx

@@ -473,9 +473,9 @@ function RolesTab() {
   const totalCount  = ALL_MODULE_KEYS.length
 
   return (
-    <div className="flex gap-5 items-start">
+    <div className="flex flex-col sm:flex-row gap-5 items-start">
       {/* Role list */}
-      <div className="w-52 shrink-0">
+      <div className="w-full sm:w-52 shrink-0">
         <div className="card overflow-hidden">
           <div className="p-3 border-b border-slate-100 dark:border-slate-700">
             <p className="text-xs font-semibold text-slate-500 dark:text-slate-400 uppercase tracking-wide">Роли</p>