feat(collective): governed invocation preview (read-only)

[m0r6aN]

Summary

• Adds read-only Invocation Preview surface to the prepared effect inspection rail — answers "what would it take to form a governed execution request?" without enabling submission or execution
• New domain layer: InvocationPreviewView DTO, repository (derives from already-fetched eligibility via Option B threading), three mock fixtures (not_available / constrained / ready), query keys
• New InvocationPreviewPanel component with status badge, requirements checklist, and constitutional footer disclaimer
• Compact "Invocation: READY / CONSTRAINED / NOT AVAILABLE" status line added to prepared effect stage card props
• Duplicate ExecutionEligibilityPanel barrel export removed

Stack Position

Observability → Explainability → Eligibility → Invocation Preview ← THIS PR

Constitutional Constraints

• No buttons, links, or onClick handlers in preview panel
• No execution language (Submit, Execute, Trigger, Run, Apply, Invoke as action)
• Footer always present: "Invocation preview does not submit or execute this effect."
• Prepared effects remain INERT regardless of readiness status

Test Plan

• TypeScript type check passes (zero errors in new files)
• Panel renders under eligibility in detail rail for prepared effect nodes
• All 5 requirements always present in deterministic order
• Correct status mapping: not_eligible → not_available, eligible + all satisfied → ready
• No interactive affordances in panel (no buttons, links, onClick)
• No forbidden execution language leaks
• Footer disclaimer always visible
• Stage card compact line renders with correct tone colors

🤖 Generated with Claude Code