Write a SpacetimeDB backend module in TypeScript that defines a product table with a BTree-indexed price column, a result table, and a reducer that filters products within a price range and writes matches to the result table.

TABLES
- product
  - Fields:
    - id: number (u64, primary key, autoInc)
    - name: string
    - price: number (u32, index btree)

- priceRangeResult
  - Fields:
    - productId: number (u64, primary key)
    - name: string
    - price: number (u32)

REDUCERS
- find_in_price_range(ctx, { minPrice: number (u32), maxPrice: number (u32) })
  - Iterate all products
  - For each product where price >= minPrice AND price <= maxPrice, insert a priceRangeResult row
