Write a SpacetimeDB backend module in TypeScript that defines a scheduled table and associated reducers.

TABLE
- tickTimer
  - Fields:
    - scheduledId: bigint (u64, primary key, auto-increment)
    - scheduledAt: ScheduleAt
  - Scheduled: tick reducer, interval of 50ms

REDUCERS
- tick: scheduled reducer that receives the tickTimer row
- init: insert initial scheduled row with 50ms interval
