Adds a user (creating one if needed) to a specific existing tenant inside an app with a specified role. Idempotent: an existing user already in the tenant is returned as-is (password is refreshed). POST /account/test/playwright/add-user-to-tenant Headers: x-playwright-api-key: <your-api-key> Body: { workspaceId, tenantId, email, password?, role?: 'ADMIN'|'MEMBER', firstName?, lastName? } Returns: { userId, email, tenantUserId, tenantId, role, created, token } - token is a fresh Bearer access token for the user, ready for SDK login. - created=true if the tenantUser was created, false if it already existed.