Write a SpacetimeDB backend module in C# that defines an event table for damage notifications and a reducer that publishes events to it.

TABLES
- DamageEvent
  - Struct: DamageEvent
  - public event table (rows exist only for the duration of the transaction, set Event = true)
  - Fields:
    - EntityId: ulong
    - Damage: uint
    - Source: string

REDUCERS
- DealDamage(ctx, ulong entityId, uint damage, string source)
  - Insert a DamageEvent row into the event table
