docs(api): document SLA/SLO targets and add NFR validation checks (#899)

[Francis6-git]

Summary

Fixes #899

This PR formalizes and documents the SLA/SLO targets for API uptime and latency across the YieldVault-RWA backend. To prevent documentation drift over time, the implementation programmatically links the markdown documentation (docs/api/SLA_SLO.md) directly to the machine-readable configuration (docs/nfr-baselines.json) via updated NFR validation scripts.

Changes Included

📄 Documentation

• docs/api/SLA_SLO.md: Created dedicated document outlining overall availability targets (99.9%), max permitted monthly downtime (43.8 mins), P95/P99 latency objectives for read/write endpoints, and error budget burn rate policies.
• README.md: Added reference link pointing to the new SLA/SLO documentation.

Configuration & Endpoint Registry

• docs/nfr-baselines.json: Added Tier 2 backend targets for latency_p99_read_ms (500ms) and latency_p99_write_ms (1200ms).
• backend/src/endpointSlaRegistry.ts: Updated EndpointSlaAnnotation interface to include p99BudgetMs and populated P99 latency budgets for all 11 endpoints.

Validation & Testing

• scripts/validate-nfr-baselines.ts:
  • Added latency bounds checks for P95/P99 metrics.
  • Implemented validateApiSlaSloDocContent to verify structure and heading completeness of SLA_SLO.md.
  • Added automated drift checking to guarantee targets in nfr-baselines.json match the public documentation verbatim.
• tests/validate-nfr-baselines.test.ts & tests/endpointSlaRegistry.test.ts:
  • Added unit tests for invalid/negative latency metrics and markdown formatting validation.
  • Verified p99BudgetMs is defined for every endpoint and strictly exceeds p95BudgetMs.

Verification

• Ran npm run validate:nfr-baselines locally — passed successfully.
• Ran Vitest suite — all NFR and registry tests passing with full coverage.
• CI checks run clean with zero regressions.

CLoses #899

[drips-wave]

@Francis6-git Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits