Add a contract test asserting API routes conform to the apiContracts schemas

[1nonlypiece]

📌 Description

src/lib/schemas/apiContracts.ts declares the response schemas for the public
API, and src/lib/backend/apiResponse.ts is the standard envelope. There are
per-route tests, but no single contract test that parses representative
responses from the read routes through the apiContracts schemas to catch
breaking shape changes.

Goal: add a schema-contract test that validates real handler responses
against the declared apiContracts schemas.

🎯 Requirements and Context

• For each covered read route (e.g. commitments list/detail, marketplace
  listings, protocol constants), call the handler and safeParse the body with
  its apiContracts schema; assert success.
• Assert the standard success envelope (success: true, data) and the error
  envelope shape for a forced error.
• Centralize a route→schema mapping so adding a route is a one-line change.
• Mock data sources consistently with tests/api/helpers.ts.

🛠️ Suggested Execution

1. Fork the repo and create a branch

git checkout -b test/api-contract-schemas

2. Implement changes

• Add tests/api/contract-schemas.test.ts (Vitest) importing schemas from
  src/lib/schemas/apiContracts.ts.

3. Test and commit

• Run the repo suite: pnpm test
• Edge cases: error envelope, optional/nullable fields, empty collections.

Example commit message

test: contract-test API routes against apiContracts schemas

✅ Guidelines

• Minimum 95% test coverage on the schemas/envelope under test.
• Clear, reviewer-friendly test names.
• Timeframe: 96 hours.

🏷️ Labels

type-testing · area-frontend · MAYBE REWARDED · GRANTFOX OSS ·
OFFICIAL CAMPAIGN

💬 Community & Support

• Join the CommitLabs contributor Discord: https://discord.gg/WV7tdYkJk
• Please introduce yourself before you start so we can avoid duplicate work.

[yunus-dev-codecrafter]

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[grantfox-oss]

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@yunus-dev-codecrafter's PR #896 was approved and merged by @1nonlypiece.

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