Write a SpacetimeDB backend module in C# that defines product types and uses them as columns in a table.

TYPES
- Struct: Address
  - Fields:
    - Street: string
    - Zip: int
- Struct: Position
  - Fields:
    - X: int
    - Y: int

TABLE
- Profile (public)
  - Struct: Profile
  - Fields:
    - Id: int (primary key)
    - Home: Address
    - Work: Address
    - Pos: Position

REDUCERS
- Seed: insert exactly one row into Profile
  - (Id=1, Home=Address{Street="1 Main", Zip=11111}, Work=Address{Street="2 Broad", Zip=22222}, Pos=Position{X=7, Y=9})
