Only expose completed refunds in booking API responses

BookingController's eager load now constrains the refunds relation to
status completed only (a new eagerLoads() layering that onto the
existing EAGER_LOADS list, applied uniformly across
index/show/store/cancel). A pending or failed refund attempt isn't
customer-facing — staff still track those via Filament's Refunds
resource, which loads the relation unconstrained.

app-modules/booking/tests/Feature/BookingCancelApiTest.php

@@ -115,6 +115,22 @@ test('cancelling a confirmed booking returns the refund it created', function ()
     expect($response->json('data.refunds.0.completed_at'))->not->toBeNull();
 });
 
+test('a pending or failed refund is not returned — only completed refunds are exposed', function () {
+    $booking = Booking::factory()->create(['user_id' => $this->owner->id, 'status' => BookingStatus::Cancelled, 'price' => 15000]);
+    $payment = Payment::factory()->completed()->create([
+        'booking_id' => $booking->id,
+        'gateway' => PaymentMethod::KbzMiniApp,
+        'amount' => 15000,
+    ]);
+    $booking->refunds()->create(['payment_id' => $payment->id, 'status' => RefundStatus::Pending, 'amount' => 15000, 'reason' => 'Booking cancellation']);
+    $booking->refunds()->create(['payment_id' => $payment->id, 'status' => RefundStatus::Failed, 'amount' => 15000, 'reason' => 'Booking cancellation']);
+
+    $this->withHeader('Authorization', "Bearer {$this->token}")
+        ->getJson("/api/v1/bookings/{$booking->booking_ref}")
+        ->assertSuccessful()
+        ->assertJsonPath('data.refunds', []);
+});
+
 test('cancelling a pending_payment booking returns an empty refunds list — no money moved yet', function () {
     $booking = Booking::factory()->create(['user_id' => $this->owner->id, 'status' => BookingStatus::PendingPayment]);