feat: implement fire-and-forget background email sending for instant API response

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

src/pages/api/contact.ts

@@ -311,7 +311,17 @@ export const POST: APIRoute = async ({ request, clientAddress }) => {
 
   // Fire-and-forget: send email in background so the user gets an instant response.
   // Errors are logged/reported but never block the HTTP reply.
+  const recipientEmail = process.env.CONTACT_EMAIL_TO || 'unknown';
+  console.log('Sending contact email to: ' + recipientEmail);
+
   sendContactEmail(formData).catch(async (err) => {
+    console.error('Background email delivery failed:', {
+      recipient: recipientEmail,
+      email: formData.email,
+      subject: formData.subject,
+      error: err instanceof Error ? err.message : String(err),
+      stack: err instanceof Error ? err.stack : undefined,
+    });
     logger.error('api.contact', 'Background email delivery failed', {
       email: formData.email,
       subject: formData.subject,
@@ -334,7 +344,7 @@ export const POST: APIRoute = async ({ request, clientAddress }) => {
   return new Response(
     JSON.stringify({
       success: true,
-      message: "Message received! We'll get back to you within 24 hours.",
+      message: 'Your message has been received. We will get back to you soon.',
     }),
     { status: 200, headers: rateLimitHeaders }
   );