Agent Skills: grey-haven-database-conventions

Apply Grey Haven database conventions - snake_case fields, multi-tenant with tenant_id and RLS, proper indexing, migrations for Drizzle (TypeScript) and SQLModel (Python). Use when designing schemas, writing database code, creating migrations, setting up RLS policies, or when user mentions 'database', 'schema', 'Drizzle', 'SQLModel', 'migration', 'RLS', 'tenant_id', 'snake_case', 'indexes', or 'foreign keys'.