feat(classes): session roster + manual waitlist promotion

Adds the roster and manual promotion controls deferred from the booking
lifecycle milestones. Businesses can now inspect who holds a seat and who
is queueing on a class session, and promote waitlisted customers by hand
— including a deliberate over-capacity override when the session is full.

Backend:
- GET /v1/catalog/class-sessions/{id}/roster — session metadata plus
  confirmed and waitlist entry lists with queue positions
- POST /v1/catalog/bookings/{id}/promote — 409 on a full session unless
  allowOverCapacity is set; 400 for non-waitlisted, 404 for missing or
  foreign bookings; reuses the shared confirm path so waitlist ledger
  rows resolve and reminder jobs re-arm
- ListBookingsBySession repository method (pgx + memory); ClassSession
  carries waitlistCount; UpcomingBooking carries classSessionId and
  waitlistPosition
- OpenAPI paths + schemas, regenerated client, catalog service tests

Frontend:
- classes tab session rows expand into a two-column roster panel with
  per-entry promote buttons and an explicit confirm-anyway step on 409
- booking detail modal shows waitlist position and offers promote for
  waitlisted bookings; list badges show #N queue positions
- CS/EN i18n keys and seeded demo roster data; demo mutations surface
  the demo notice

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/frontend/src/routes/dashboard/dashboard-data.ts

@@ -48,7 +48,7 @@ function createDemoData(i18n: ReturnType<typeof useI18n>) {
     { id: "b6", customerName: customers[0].name, customerEmail: customers[0].email, service: services[1], status: "confirmed", startsAt: fmt(at(3, 10)), endsAt: fmt(at(3, 11)), reference: "BOK-006", location: salonA, staffName: staff1, notes: "" },
     { id: "b8", customerName: customers[2].name, customerEmail: customers[2].email, service: services[3], status: "pending", startsAt: fmt(at(4, 9)), endsAt: fmt(at(4, 10)), reference: "BOK-008", location: salonA, staffName: staff2, notes: "" },
     { id: "b9", customerName: customers[3].name, customerEmail: customers[3].email, service: services[0], status: "confirmed", startsAt: fmt(at(5, 11)), endsAt: fmt(at(5, 12)), reference: "BOK-009", location: salonA, staffName: staff1, notes: "" },
-    { id: "b13", customerName: customers[0].name, customerEmail: customers[0].email, service: cs ? "Jóga pro začátečníky" : "Beginner yoga", status: "waitlisted", startsAt: fmt(at(3, 18)), endsAt: fmt(at(3, 19)), reference: "BOK-013", location: salonA, staffName: "", notes: "" },
+    { id: "b13", customerName: customers[0].name, customerEmail: customers[0].email, service: cs ? "Jóga pro začátečníky" : "Beginner yoga", status: "waitlisted", waitlistPosition: 1, startsAt: fmt(at(3, 18)), endsAt: fmt(at(3, 19)), reference: "BOK-013", location: salonA, staffName: "", notes: "" },
   ];
 
   return {