- C-1: Add tenant_id to settings unique index to prevent cross-tenant conflicts
- C-2: Move pg_advisory_xact_lock inside the transaction for correct concurrency
(previously lock was released before the numbering transaction started)
- H-5: Add CORS middleware (permissive for dev, TODO: restrict in production)
- users with partial unique index on (tenant_id, username) WHERE deleted_at IS NULL
- user_credentials, user_tokens with FK cascade
- roles, permissions with composite unique (tenant_id, code)
- role_permissions, user_roles junction tables
- organizations (self-ref tree), departments (tree + org FK), positions
- All tables include standard fields: id, tenant_id, timestamps, soft delete, version
