audit: 2026-05-30 full-codebase audit — report, issues, docs, runbooks

Full-codebase-audit 2026-05-30 outputs:
- Audit report: 09 - Audits/Full Codebase Audit - 2026-05-30.md
- 81 issue files ISSUE-055..135 (decisions + 1 skipped no-brainer).
- Scanner docs from scratch (was zero): architecture, data model, API ref, payment
  flow, operations runbook + repo README.
- Doc-sync updates across API reference, data models, flows, design system.
- Secret Rotation Runbook (08 - Operations) for the exposed credentials.
- Reusable workflow guide (07 - Development) + .claude/workflows/full-codebase-audit.js.

Issues remain status:open intentionally — the code fixes are uncommitted-then-committed
working-tree changes per repo and aren't "resolved" until merged/deployed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

03 - API Reference/API Overview.md

@@ -34,7 +34,9 @@ This page is the entry point for the API. See the individual service pages for e
 
 The base port is set via `PORT` env var; in `development` it defaults to `5001`. CORS is restricted to `process.env.FRONTEND_URL` and credentials are allowed (`cors({ origin, credentials: true })` in `app.ts`).
 
-Health check (not under `/api`): `GET /health` → `{ success, message, timestamp, environment, version }`.
+Health checks:
+- `GET /health` (not under `/api`) → `{ success, message, timestamp, environment, version }` — used by Docker and Gatus.
+- `GET /api/health` (added in commit `44579d6`, backend v2.6.49) → deeper JSON with database and Redis connectivity status, plus the version string. Used by Gatus monitoring.
 
 API discovery endpoint: `GET /api` → returns a map of available service prefixes.