Adds the plumbing every other booking ticket builds on: resources,
services, users, and password_reset_tokens tables, plus the clients
columns (slug, timezone, auto_confirm, ics_token) and the bookings
resource_id/EXCLUDE-constraint double-booking protection described in #14.
booking_db.py is the only place raw SQL runs against these tables --
every function takes client_id and injects the tenant filter itself,
and create/update_booking additionally verify the resource_id belongs
to that client before writing, closing a guessed-ID cross-tenant hole.
Tests spin up a real throwaway Postgres 16 container (matching prod) and
exercise the EXCLUDE constraint, tenancy isolation, and password-reset
single-use semantics end to end, per #14's "real Postgres, no mocking"
testing decision.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
mivanchenko
b5c0fc8a5a