Add API benchmark suite

[s0584273828-ctrl]

/claim #30

Summary

• Add a dependency-light API benchmark suite under benchmarks/ covering /health and every mounted /api/* route.
• Add realistic synthetic payloads, generated benchmark admin auth, threshold gates, JSON output, and Markdown output.
• Add root commands: npm run benchmark and npm run benchmark:smoke.

Smoke benchmark summary

Committed full report: benchmarks/results/latest.md and benchmarks/results/latest.json.

Endpoint coverage	Requests each	Error rate	Gate
21 endpoints (/health + all /api/*)	3	0%	pass

Slowest smoke p99 in the committed run: health at 15.42 ms; upload p99 was 1.98 ms.

Validation

• npm run benchmark:smoke -> all 21 endpoint gates passed
• node --check benchmarks/run-api-benchmarks.mjs
• node --check benchmarks/scenarios.mjs
• git diff --check

Prepared with AI assistance and manually reviewed before submission.

[s0584273828-ctrl]

Follow-up: added a GitHub Actions smoke workflow for the API benchmark suite after refreshing the token with the required workflow scope.\n\nValidation:\n- npm run benchmark:smoke\n- git diff --check