Write a SpacetimeDB backend module in Rust that defines one table and an init reducer that seeds rows on database initialization.

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