refactor(layout): apply full-width layout to all pages

- Remove max-w-7xl containers from all page templates
- Replace with w-full for full-screen width utilization
- Maintain padding for readability
- Admin templates: modify inner content div only (preserve sidebar layout)

templates/admin_users.templ

@@ -22,7 +22,7 @@ templ AdminUsers(currentUser User, users []User, adminCount int) {
             @AdminSidebar(currentUser, "/admin/users")
 
             <main class="flex-1 p-8">
-                <div class="max-w-7xl">
+                <div class="w-full">
                     <h1 class="text-3xl font-bold mb-2" style="color: var(--text-primary)">User Management</h1>
                     <p style="color: var(--text-secondary)">Manage user accounts and permissions</p>
                 </div>