fix(routes): wrap marketplace plugin and dispute responses in envelopes

[lienhoatienphung-svg]

Closes #1249

Summary

Updates src/routes/marketplace/plugins.ts and src/routes/billing/disputes.ts so every JSON response is wrapped in the standard successEnvelope / errorEnvelope (via next(AppError)), updates docs/openapi.json to document /api/marketplace/plugins and /api/billing/disputes with standard envelope schemas, and expands src/contracts/responseEnvelope.contract.test.ts to verify both route families.

Acceptance Criteria Mapping

• GET /api/marketplace/plugins and POST /api/marketplace/plugins/:pluginId/install return { success: true, data, requestId, timestamp } on success and { success: false, error, requestId, timestamp } on failure: Implemented using successEnvelope and typed AppError subclasses (NotFoundError, ConflictError).
• POST /api/billing/disputes and GET /api/billing/disputes/:id return the standard envelope on all status codes: Implemented using successEnvelope and BadRequestError / NotFoundError / ConflictError.
• src/contracts/responseEnvelope.contract.test.ts includes both route families and passes: Added contract assertions covering both success and error envelopes.

Validation

• npx jest src/contracts/responseEnvelope.contract.test.ts src/routes/marketplace/plugins.test.ts src/routes/billing/disputes.test.ts --no-cache (all pass).

---

Payout Wallet (Base Mainnet USDC / EVM): 0x3806cd592a508d1992Ed007C2F53de251C2E7452