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: int (primary key)
    - Name: string
    - Age: int
    - Active: bool

REDUCERS
- Init: insert exactly these rows on initialization
  - (Id=1, Name="Alice", Age=30, Active=true)
  - (Id=2, Name="Bob",   Age=22, Active=false)
