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>

database/seeders/AdminSeeder.php

@@ -15,7 +15,7 @@ class AdminSeeder extends Seeder
             [
                 'name'     => 'Admin eCert MBIP',
                 'password' => Hash::make('Admin@MBIP2025!'),
-                'is_admin' => true,
+                'role'     => 'super_admin',
             ]
         );