Configure Route-Level Rate Limiting for Auth and Settlement Endpoints

[Cjay-Cyber-2]

Description

To protect against authentication brute-force attacks and automated settlement spam, dedicated rate limits need to be applied to sensitive authentication and transaction submission routes using @fastify/rate-limit.

Context & Requirements

• Fastify rate limit plugin (@fastify/rate-limit) is installed in dependencies.
• Global defaults should remain, but strict rate limits must be configured for high-risk endpoints:
  • SEP-10 challenge generation (POST /auth/challenge): max 10 requests per minute per IP.
  • SEP-10 token exchange (POST /auth/token): max 10 requests per minute per IP.
  • Settlement transaction submission (POST /settlements/submit): max 20 requests per minute per user/IP.

Acceptance Criteria

• Configure custom config.rateLimit route options on target endpoint handlers in src/routes/auth.ts and src/routes/settlements.ts.
• Ensure rate limit headers (x-ratelimit-limit, x-ratelimit-remaining, x-ratelimit-reset) are returned in HTTP responses.
• Return standard Fastify 429 Too Many Requests response payload on threshold breach.
• Ensure rate limits do not impact internal service calls or integration test runs.
• Write integration test validating 429 status code response upon exceeding limit.

Implementation Guidance

• Register and configure route-specific limits using Fastify plugin route config objects.
• Keep rate limit definitions clear and configurable via environment settings if applicable.
• Ensure test suite disables or handles rate limiters properly during integration test execution.

Testing & Validation

• Run npm test and npm run test:integration to ensure standard tests pass.
• Add an integration test in tests/rateLimit.test.ts firing rapid requests to verify 429 response behavior.

Submission Guidelines

• Open a PR that includes "Closes #".
• Ensure task assignment before work commences.
• Run npm run lint before submitting.

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[chiemezie1]

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[afeezorobsco-cyber]

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[grantfox-oss]

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@afeezorobsco-cyber's PR #297 was approved and merged by @Cjay-Cyber-2.

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