Backlog: Rumah Singgah booking + 1 night/month rule

TL;DR

Authenticated user can book one night for Rumah Singgah; server rejects a second booking in the same calendar month for that user.

Description

• Rules: [[Projects/lumendev-museum-ibu-marsinah/context/rumah-singgah-booking-rules|booking rules doc]].
• UI: date picker (single night), confirmation, ID error messages.
• Persistence: MongoDB bookings collection (shape TBD; include userId, date, status).

Acceptance Criteria

• Unauthenticated visitor cannot create booking.
• First booking in a month succeeds for user.
• Second booking same month returns friendly ID error; no double insert.
• User can view own upcoming/past bookings (minimal list).

Priority

• p0 — core differentiator vs static landing.

Dependencies

• Blocked by: [[Projects/lumendev-museum-ibu-marsinah/backlog/p0-auth-admin-user-roles|auth]]
• Blocked by: [[Projects/lumendev-museum-ibu-marsinah/backlog/p0-scaffold-nextjs-repo-vercel|scaffold]]