Problem

Port Workflow input nodes support Slack notifications natively ("target": "slack"), including in-Slack review/respond via the Port Slack app. The Terraform port_workflow resource still validates node.input.notifications.target as only email or webhook (documented on the registry; same gap in Pulumi). Customers who manage workflows in Terraform cannot declare the same Slack responder path they configure in the UI.

Requested change

Add slack to the allowed values for node.input.notifications.target on port_workflow (and keep schema/docs in sync). When target = "slack", no extra fields should be required beyond what the API/docs expect for Slack input-node notifications.

Why it matters

Parity between UI/API and IaC. Without it, teams fall back to email (and optional separate Slack posts) and lose the native in-Slack approve/respond UX for Terraform-managed workflows.