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>

src/models/tickets/admin/admin.router.ts

@@ -0,0 +1,35 @@
+import express, {Request, Response} from 'express';
+import {requireAdminAuth} from '../tickets.auth';
+import {vouchersAdminRouter} from './vouchers.admin.router';
+import {redemptionsAdminRouter, voucherHistoryRouter} from './redemptions.admin.router';
+import {eventsAdminRouter} from './events.admin.router';
+
+export const adminRouter = express.Router();
+
+// Applied once at the top of the admin router tree - every route below
+// requires a valid admin session (mirrors Feedback's admin.router.ts).
+adminRouter.use(requireAdminAuth);
+
+/**
+ * @swagger
+ * /tickets/admin/me:
+ *      get:
+ *          summary: Validate the current admin session
+ *          tags: [tickets-admin]
+ *          parameters:
+ *              - $ref: '#/components/parameters/SessionIdHeader'
+ *              - $ref: '#/components/parameters/SessionKeyHeader'
+ *          responses:
+ *              200:
+ *                  description: Success
+ *              401:
+ *                  description: Unauthorized
+ */
+adminRouter.get('/me', (req: Request, res: Response) => {
+	res.status(200).send({email: res.locals.admin.email, fullName: res.locals.admin.displayName});
+});
+
+adminRouter.use('/vouchers', vouchersAdminRouter);
+adminRouter.use('/vouchers', voucherHistoryRouter);
+adminRouter.use('/redemptions', redemptionsAdminRouter);
+adminRouter.use('/events', eventsAdminRouter);