Module role_delegation_repository_impl 

PostgreSQL implementation of RoleDelegationRepository (Story 3.5).

Persists delegated role assignments inside the existing user_roles table using the two new columns introduced by migration 20260605030000_extend_user_roles_delegation.sql:

• valid_until TIMESTAMPTZ (NULL = permanent native row)
• delegated_from_user_id UUID (NULL = native row)

Structs

PostgresRoleDelegationRepository