Contract SDK: price and decimal scaling helpers

[0xMegie]

Area: packages/contracts/src/scaling.ts

Goal: Verify protocol-scale price/amount scaling stays lossless.

Tasks:

• Add fixtures converting human amounts to/from protocol decimals.
• Cover 1e30 USD scale and token decimal boundaries.
• Assert round-trips never downcast through JavaScript number.

Acceptance:

• Values stay as bigint/string; no precision loss.
• bun run --cwd packages/contracts test passes.

[ghost-cy829]

I would like to work on this issue. I have experience with Rust and Soroban smart contract development. I will follow the acceptance criteria and add tests. Excited to contribute. Kindly assign.

[pablowizzy24]

Smart contracts often work with integers instead of floating-point numbers to avoid precision errors. Price and decimal scaling helpers make it easier to convert values into the correct format for calculations.