Make workflow checklist go-to configurable

[lyzno1]

Summary

The workflow checklist cards always show a hover-only "Go To" affordance and their click behavior is fixed to selecting the node. We need to make this reusable/configurable.

Requirements

• Allow callers of the checklist component to explicitly hide/disable the Go To affordance via props (independent of the computed canNavigate check).
• Allow callers to provide a custom click handler for checklist items; default should remain selecting the node.
• Ensure entries that point to missing/blocked nodes (e.g., plugin-not-installed items) can suppress Go To when navigation is not possible.

Current behavior

• Go To visibility is driven solely by canNavigate and a hover opacity toggle; no prop to disable it.
• Click handling is hard-coded to handleNodeSelect within handleChecklistItemClick, so it cannot be overridden.

Acceptance criteria

• Checklist UI exposes props to toggle the Go To affordance and to inject a custom click handler.
• Existing behavior remains unchanged when new props are not provided.
• Plugin-not-installed checklist entries do not render Go To and do not attempt navigation.