feat(bookings): dashboard cancellation and waitlist promotion

- POST /v1/catalog/bookings/{id}/cancel lets businesses cancel
  tenant-owned bookings; two-step confirm in the detail modal
- Shared PromoteWaitlist helper promotes earliest waitlisted bookings
  when a class seat frees, on both dashboard and customer cancel paths;
  promoted customers get a confirmation email, waitlist ledger marked
  resolved
- waitlisted status surfaced in bookings UI: stats card, filter, warning
  badge, demo seed, CS+EN strings
- BookingRecord gains created_at for fair ordering; GetBookingByID and
  ResolveWaitlistEntry added to the repository surface

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project.md

@@ -75,6 +75,13 @@
   - dashboard zones page gained a staff-scope selector on the working-hours tab (business-wide vs individual schedule) and a Classes tab with template create/delete and session scheduling
   - normalized `availability_rules` time columns (`HH:MM:SS`) down to the `HH:MM` API contract in the service layer
   - remaining: live staging validation
+- `[done/partial]` Milestone 11: Booking lifecycle — dashboard cancellation and waitlist promotion
+  - businesses can cancel bookings from the dashboard (`POST /v1/catalog/bookings/{id}/cancel`), tenant-checked, with a two-step confirm in the booking detail modal
+  - cancelling a class booking (dashboard or customer self-service) now promotes the earliest waitlisted bookings while free capacity remains, ordered by booking `created_at`; promoted customers receive a confirmation email, cancelled customers a cancellation email
+  - shared `bookings.PromoteWaitlist` helper drives both cancel paths; waitlist ledger entries are marked resolved on promotion
+  - bookings surface the `waitlisted` status: stats card, filter option, warning-tone badge, demo seed entry; `dashboard.{status}` interpolation resolves the new i18n key automatically
+  - `BookingRecord` now carries `created_at` (needed for fair waitlist ordering); `GetBookingByID` added to the repository surface
+  - remaining: live staging validation; waitlist position display and manual promotion controls are not yet exposed
 
 ## Overview
 Bookra is a Czech-first booking SaaS for small local service businesses. It targets salons, massage therapists, small clinics, repair shops, and small studios/clubs that need a simple public booking flow, internal schedule management, reminders, and basic business reporting without becoming a full ERP.