Add admin user management and improve UX

Features:
- Add user management for admins (CRUD operations)
- Add is_admin column to users table
- Add AdminMiddleware for authorization
- Add admin routes and views
- Add artisan command: user:set-admin

Improvements:
- Fix Quick Switcher: add x-data for Alpine.js dispatch
- Fix Quick Switcher: close on outside click
- Redirect non-admin users to front page after login
- Add Knowledge Base link in dashboard navigation
- Change app logo from Laravel to book icon

src/bootstrap/app.php

@@ -11,7 +11,9 @@
         health: '/up',
     )
     ->withMiddleware(function (Middleware $middleware): void {
-        //
+        $middleware->alias([
+            'admin' => \App\Http\Middleware\AdminMiddleware::class,
+        ]);
     })
     ->withExceptions(function (Exceptions $exceptions): void {
         //