Add Tickets domain for the voucher-based ticket shop

New domain mirroring the Feedback module's conventions: single-use voucher
codes (wildcard + personalized), redemption with race-safe capacity and
deadline enforcement, admin CRUD for vouchers/redemptions/event settings
with an audit trail, and reuse of the existing Calendar session auth.

Backend pieces:
- Tickets domain (public redeem flow, admin vouchers/redemptions/events)
- Calendar events.service.ts: add getEventById
- Mailer: attachment/HTML support, fix a shared-mutable-state race
- Per-event capacity/deadline/address settings, with an "address
  required" option on top of "address collected"
- Email format validation on redeem and admin voucher/redemption input
- Docker Compose dev stack (MariaDB + seed data) for local testing

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app.ts

@@ -8,6 +8,7 @@ import logger from './src/middleware/logger';
 // Router imports
 import {calendarRouter} from './src/models/calendar/Calendar.router';
 import {feedbackRouter} from './src/models/feedback/Feedback.router';
+import {ticketsRouter} from './src/models/tickets/Tickets.router';
 
 
 let cors = require('cors');
@@ -36,7 +37,8 @@ app.use(express.json());
 let allowedHosts = [
 	'https://www.nachklang.art',
 	'https://calendar.nachklang.art',
-	'https://feedback.nachklang.art'
+	'https://feedback.nachklang.art',
+	'https://tickets.nachklang.art'
 ];
 const isDev = process.env.NODE_ENV !== 'production';
 const localhostRegex = /^http:\/\/localhost:\d+$/;
@@ -104,6 +106,7 @@ app.use(
 // Add routers
 app.use('/calendar', calendarRouter);
 app.use('/feedback', feedbackRouter);
+app.use('/tickets', ticketsRouter);
 
 // this is a simple route to make sure everything is working properly
 app.get('/', (req: express.Request, res: express.Response) => {