feat: Add AGB PDF attachment to booking confirmation emails

- Extend email system to support file attachments
- Add sendEmailWithAGB() function that automatically attaches AGB.pdf
- Implement AGB PDF caching for better performance
- Update booking confirmation email template with AGB notice
- Add visual highlight box in HTML email with AGB information
- Update email subject to indicate AGB attachment
- Include AGB reference in both HTML and text versions
- Ensure legal compliance by automatically sending terms with confirmations

Changes:
- email.ts: Add attachment support and AGB PDF integration
- email-templates.ts: Add AGB notice to confirmation emails
- bookings.ts: Use sendEmailWithAGB for confirmed bookings
- German localization for admin treatments component

src/server/rpc/bookings.ts

@@ -3,7 +3,7 @@ import { z } from "zod";
 import { randomUUID } from "crypto";
 import { createKV } from "@/server/lib/create-kv";
 import { createKV as createAvailabilityKV } from "@/server/lib/create-kv";
-import { sendEmail } from "@/server/lib/email";
+import { sendEmail, sendEmailWithAGB } from "@/server/lib/email";
 import { renderBookingPendingHTML, renderBookingConfirmedHTML, renderBookingCancelledHTML } from "@/server/lib/email-templates";
 
 const BookingSchema = z.object({
@@ -146,10 +146,10 @@ const updateStatus = os
     try {
       if (input.status === "confirmed") {
         const html = await renderBookingConfirmedHTML({ name: booking.customerName, date: booking.appointmentDate, time: booking.appointmentTime });
-        await sendEmail({
+        await sendEmailWithAGB({
           to: booking.customerEmail,
-          subject: "Dein Termin wurde bestätigt",
-          text: `Hallo ${booking.customerName},\n\nwir haben deinen Termin am ${booking.appointmentDate} um ${booking.appointmentTime} bestätigt.\n\nBis bald!\nStargirlnails Kiel`,
+          subject: "Dein Termin wurde bestätigt - AGB im Anhang",
+          text: `Hallo ${booking.customerName},\n\nwir haben deinen Termin am ${booking.appointmentDate} um ${booking.appointmentTime} bestätigt.\n\nWichtiger Hinweis: Die Allgemeinen Geschäftsbedingungen (AGB) findest du im Anhang dieser E-Mail. Bitte lies sie vor deinem Termin durch.\n\nBis bald!\nStargirlnails Kiel`,
           html,
           cc: process.env.ADMIN_EMAIL ? [process.env.ADMIN_EMAIL] : undefined,
         });