Write a SpacetimeDB backend module in Rust that defines one table and two reducers: one that inserts a row and one that deletes a row.

TABLE
- user
  - Struct: User
  - Fields:
    - id: u64 (primary key, auto_inc)
    - name: String
    - age: i32
    - active: bool

REDUCERS
- insert_user: given name:String, age:i32, active:bool, insert a new row (id is auto-assigned)
- delete_user: given id:u64, delete the row in user with that id
