Add CancelReservationHandler (DELETE /api/bookings/reserve) to release authenticated user's active reservation. Register route in main.go. Add background goroutine for periodic reservation cleanup using CleanupOldReservations. Add idx_time_blockers_created_at index and extend anon cleanup to cover edit_request reservations in init-script.sql. Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent) Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>