XSpada Central Auth

Service health: configured

• GET /api/auth/* — Better Auth handler (pass X-Xspada-App-Id for OTP email)
• POST /api/auth/bridge-member — body { "app_id": "..." }
• POST /api/auth/finish-org — body includes app_id, org + member fields

Local dev: copy .env.example to .env.local. See docs/auth-architecture.md.