test: add guest booking, reservation, and anonymization tests
New tests: guest user creation (success, duplicate email, registered collision),
guest booking flow (success, missing user_id, non-guest user_id, deposit bypass),
reservation lifecycle (logged-in, anonymous, replace, validation, conflict detection,
dual cleanup), anonymization (6mo threshold, pending exclusion).
Fixes: deposit advance rule 48h→24h (stale test), time-based test flakiness
(2h→72h offsets), handler confusion in no-show tests, enum type casting for
booking status.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
popertotsandSisyphus
52ca9b425b