Write a SpacetimeDB backend module in C# that defines one table and an Init reducer that seeds rows on database initialization.

TABLE
- User
  - Struct: User
  - Fields:
    - Id: ulong (primary key, auto-increment)
    - Name: string
    - Age: int
    - Active: bool

REDUCERS
- Init: insert exactly these rows on initialization (IDs are auto-assigned)
  - (Name="Alice", Age=30, Active=true)
  - (Name="Bob",   Age=22, Active=false)
