enhanced gas and amount validation

[qvkare]

Enhances the validation logic for gas and amount parameters in the Quote API, ensuring robust handling of edge cases and preventing potential overflow issues.

1. Amount Validation (quote-schema.ts)

• Added BigInt extension for amount validation
• Implemented checks for:
  • Negative amounts (rejected)
  • Zero amounts (rejected)
  • Decimal values (rejected)
  • Values exceeding uint256 (rejected)
  • Maximum uint256 value (accepted)

// Added MAX_UINT256 constant
export const MAX_UINT256 = BigInt('0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff')

// Enhanced QuoteQueryParamsJoi schema
amount: Joi.string()
  .pattern(/^[0-9]+$/)
  .custom((value, helpers) => {
    try {
      const amount = BigInt(value)
      if (amount <= 0n) {
        return helpers.error('Amount must be greater than 0')
      }
      if (amount > MAX_UINT256) {
        return helpers.error('Amount must not exceed maximum uint256 value')
      }
      return value
    } catch {
      return helpers.error('Invalid amount format')
    }
  })

2. Test Coverage (quote.test.ts)

Added comprehensive test cases for amount validation:

// Test cases for amount validation
it('rejects negative amounts')
it('rejects zero amounts')
it('rejects decimal values')
it('rejects amounts larger than uint256')
it('accepts maximum uint256 value')