feat: two-role system — super_admin & admin program (Fasa 12)

- Replace is_admin boolean with role enum('super_admin','admin') via migration
- ProgramPolicy: admin program can only view/edit/delete own programs
- EnsureIsAdmin: accepts both roles; EnsureSuperAdmin: super_admin only
- UserController + views: super_admin can manage admin accounts
- Sidebar: user management link & role badge gated on isSuperAdmin()
- Fix Controller base class: add AuthorizesRequests trait
- Fix tests: replace nonAdmin() (invalid enum) with adminProgram() against super_admin-only route

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

app/Http/Controllers/Controller.php

@@ -2,7 +2,9 @@
 
 namespace App\Http\Controllers;
 
+use Illuminate\Foundation\Auth\Access\AuthorizesRequests;
+
 abstract class Controller
 {
-    //
+    use AuthorizesRequests;
 }