Fix order_created email by waiting for send-notification before navigation

The early termination issue was caused by the page navigating away before
the send-notification function call could complete. Changed from fire-and-forget
to awaiting the email send result before redirecting.

Changes:
- Checkout.tsx: Changed send-notification call to use await instead of .then()/.catch()
- Now waits for email send to complete before navigating to order detail page
- Email failures are caught in try/catch but navigation still proceeds

Technical details:
- Browser was terminating pending requests when navigate() was called immediately
- Early termination: isolate warning indicated function was being killed mid-execution
- Awaiting the function call ensures it completes before page navigation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/pages/Checkout.tsx

@@ -116,12 +116,13 @@ export default function Checkout() {
         throw new Error(paymentError.message || 'Gagal membuat pembayaran');
       }
 
-      // Send order_created email with QR code (non-blocking, fire-and-forget)
+      // Send order_created email with QR code (wait for completion before navigating)
       console.log('[CHECKOUT] About to send order_created email for order:', order.id);
       console.log('[CHECKOUT] User email:', user.email);
       console.log('[CHECKOUT] Payment data QR string:', paymentData?.qr_string);
 
-      supabase.functions.invoke('send-notification', {
+      try {
+        const result = await supabase.functions.invoke('send-notification', {
           body: {
             template_key: 'order_created',
             recipient_email: user.email,
@@ -144,15 +145,14 @@ export default function Checkout() {
               qr_expiry_time: paymentData?.expired_at ? new Date(paymentData.expired_at).toLocaleString('id-ID') : ''
             }
           }
-      }).then(result => {
-        console.log('[CHECKOUT] send-notification called successfully:', result);
-      }).catch(err => {
-        console.error('[CHECKOUT] Failed to send order_created email:', err);
-        console.error('[CHECKOUT] Error details:', JSON.stringify(err));
-        // Don't block checkout flow if email fails
         });
+        console.log('[CHECKOUT] send-notification called successfully:', result);
+      } catch (emailErr) {
+        console.error('[CHECKOUT] Failed to send order_created email:', emailErr);
+        // Don't block checkout flow if email fails
+      }
 
-      console.log('[CHECKOUT] Order creation email call initiated');
+      console.log('[CHECKOUT] Order creation email call completed');
 
       // Clear cart and redirect to order detail page to show QR code
       clearCart();