Notify transfer owners when files enter grace period.

Send grace-entered and countdown emails to owners alongside recipient grace milestones so unpaid transfers get clear wallet top-up reminders before deletion.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/Feature/TransferBillingTest.php

@@ -4,9 +4,11 @@ namespace Tests\Feature;
 
 use App\Models\Transfer;
 use App\Models\User;
+use App\Notifications\TransferOwnerGraceNotification;
 use App\Services\Transfer\TransferBillingService;
 use Illuminate\Foundation\Testing\RefreshDatabase;
 use Illuminate\Support\Facades\Http;
+use Illuminate\Support\Facades\Notification;
 use Illuminate\Support\Str;
 use Tests\Concerns\FakesTransferBilling;
 use Tests\TestCase;
@@ -18,6 +20,8 @@ class TransferBillingTest extends TestCase
 
     public function test_failed_renewal_enters_grace_period(): void
     {
+        Notification::fake();
+
         $user = User::create([
             'public_id' => (string) Str::uuid(),
             'name' => 'Grace User',
@@ -46,6 +50,8 @@ class TransferBillingTest extends TestCase
         $this->assertNotNull($transfer->grace_ends_at);
         $this->assertTrue($transfer->grace_ends_at->isFuture());
         $this->assertTrue($transfer->isAccessible());
+
+        Notification::assertSentTo($user, TransferOwnerGraceNotification::class);
     }
 
     public function test_transfer_past_grace_period_is_deleted(): void