R8. GET /api/health → 200 { "status": "ok", "uptimeSeconds": <number> }. R9. ALL error responses use the { "errors": { ... } } shape consistently (never a bare string, never {error:"..."}). R10. All timestamps in ISO 8601.
GET /api/health
{ "status": "ok", "uptimeSeconds": <number> }
{ "errors": { ... } }
{error:"..."}