Write a SpacetimeDB backend module in C# that defines a product type and uses it in a table.

TYPES
- Struct: Score
  - Fields:
    - Left: int
    - Right: int

TABLE
- Result (public)
  - Struct: Result
  - Fields:
    - Id: int (primary key)
    - Value: Score

REDUCERS
- SetScore: given id:int, left:int, right:int, insert exactly this row into Result
  - (Id=id, Value=Score{Left=left, Right=right})
