[olawaleakanbi035-maker]

• Create API contract integration test suite in tests/api/quotes-contract.test.ts covering POST /api/v1/quotes and related endpoints.
• Minimum Amount: Enforces minNgnAmount limits (HTTP 400 for amounts under threshold).
• Maximum Amount: Enforces maxNgnAmount and maxQuoteUsdcAmount limits.
• Fee Rounding: Validates platform fee rounding and net source calculations.
• USDC Truncation: Guarantees destination amount payout conforms to 6-decimal USDC precision bounds.
• Spread Application: Verifies exchange rate spread calculations in quotes.
• Network Fee Calculation: Asserts network fee presence and values in response payload.
• Stale FX Rate: Validates HTTP 502 error responses when FX provider rate is stale.
• Quote Expiration: Validates automatic status transition to EXPIRED and order rejection for expired quotes.
• Quote Reuse Prevention: Validates single-use quote restriction when placing orders.
• Quote/Order Mismatch: Verifies created orders strictly derive values from server quotes.
• Liquidity Availability: Validates liquidityAvailable response status and order rejection when pool is depleted.
• Malformed Payloads: Validates HTTP 400 validation error responses for bad parameters, negative/zero amounts, invalid UUIDs, and unsupported currency pairs.

Summary of Changes

Brief description of what this PR introduces, fixes, or refactors in luminarail-backend.

Related Contributor Issue: Closes #

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Type of Change

• Bug fix (non-breaking change fixing an API issue)
• New feature (non-breaking change adding an endpoint or worker feature)
• Breaking change (change breaking existing API contracts or schema)
• Documentation update
• Refactoring / Test coverage addition

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Verification & Quality Checklist

• TypeScript check passes cleanly: npm run type-check
• ESLint passes cleanly: npm run lint
• Production build compiles cleanly: npm run build
• All Vitest tests pass cleanly: npm test
• Zod schema validation added for new request parameters
• Financial amounts use string representation / Decimal handling (no float rounding)
• Idempotency-Key headers respected for financial mutations
• No API keys, JWT secrets, database credentials, or Stellar seed phrases committed

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Test Verification Output

npm test
# Paste test results here