Feature: Admin kann Nachrichten an Kunden senden

- Neues Email-Template für Kundennachrichten
- RPC-Funktion sendCustomerMessage für zukünftige Termine
- UI: Nachricht-Button und Modal in Admin-Buchungen
- Email mit BCC an Admin für Monitoring
- HTML-Escaping für sichere Nachrichtenanzeige
- Detailliertes Logging für Debugging

src/server/lib/email.ts

@@ -6,6 +6,7 @@ type SendEmailParams = {
   from?: string;
   cc?: string | string[];
   bcc?: string | string[];
+  replyTo?: string | string[];
   attachments?: Array<{
     filename: string;
     content: string; // base64 encoded
@@ -130,22 +131,27 @@ export async function sendEmail(params: SendEmailParams): Promise<{ success: boo
     return { success: false };
   }
 
+  const payload = {
+    from: params.from || DEFAULT_FROM,
+    to: Array.isArray(params.to) ? params.to : [params.to],
+    subject: params.subject,
+    text: params.text,
+    html: params.html,
+    cc: params.cc ? (Array.isArray(params.cc) ? params.cc : [params.cc]) : undefined,
+    bcc: params.bcc ? (Array.isArray(params.bcc) ? params.bcc : [params.bcc]) : undefined,
+    reply_to: params.replyTo ? (Array.isArray(params.replyTo) ? params.replyTo : [params.replyTo]) : undefined,
+    attachments: params.attachments,
+  };
+
+  console.log(`Sending email via Resend: to=${JSON.stringify(payload.to)}, subject="${params.subject}"`);
+
   const response = await fetch("https://api.resend.com/emails", {
     method: "POST",
     headers: {
       "Authorization": `Bearer ${RESEND_API_KEY}`,
       "Content-Type": "application/json",
     },
-    body: JSON.stringify({
-      from: params.from || DEFAULT_FROM,
-      to: Array.isArray(params.to) ? params.to : [params.to],
-      subject: params.subject,
-      text: params.text,
-      html: params.html,
-      cc: params.cc ? (Array.isArray(params.cc) ? params.cc : [params.cc]) : undefined,
-      bcc: params.bcc ? (Array.isArray(params.bcc) ? params.bcc : [params.bcc]) : undefined,
-      attachments: params.attachments,
-    }),
+    body: JSON.stringify(payload),
   });
 
   if (!response.ok) {
@@ -153,6 +159,9 @@ export async function sendEmail(params: SendEmailParams): Promise<{ success: boo
     console.error("Resend send error:", response.status, body);
     return { success: false };
   }
+  
+  const responseData = await response.json().catch(() => ({}));
+  console.log("Resend email sent successfully:", responseData);
   return { success: true };
 }