﻿Write a SpacetimeDB backend module in Rust that defines three tables with basic columns.

TABLES
- user
  - Struct: User
  - Fields:
    - id: i32 (primary key)
    - name: String
    - age: i32
    - active: bool

- product
  - Struct: Product
  - Fields:
    - id: i32 (primary key)
    - title: String
    - price: f32
    - in_stock: bool

- note
  - Struct: Note
  - Fields:
    - id: i32 (primary key)
    - body: String
    - rating: i64
    - pinned: bool
