Write a SpacetimeDB backend module in TypeScript that schedules a reducer and allows canceling it before it fires.

TABLE
- cleanupJob
  - Fields:
    - scheduledId: u64 (primary key, auto-increment)
    - scheduledAt: scheduleAt
  - Scheduling: scheduled to call the run_cleanup reducer

REDUCERS
- run_cleanup: scheduled reducer triggered by cleanupJob (receives a cleanupJob row argument, does nothing)
- init: inserts one row into cleanupJob with a 60-second interval (60_000_000n microseconds)
- cancel_cleanup(ctx, { scheduledId: u64 }): deletes the cleanupJob row with the given scheduledId, canceling the pending scheduled call
