- Add migration 030 with sites table, RLS policy, and device site_id FK
- Add Site SQLAlchemy model with tenant isolation
- Add site_id nullable FK and relationship to Device model
- Add sites relationship to Tenant model
- Register Site in models __init__.py
- Add SiteCreate, SiteUpdate, SiteResponse, SiteListResponse schemas
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
