Record plain gx cockpit cleanup proof (#513)

The implementation PR merged and branch cleanup completed after the original task commit, so the OpenSpec checklist now records the actual PR, merge commit, branch deletion, and worktree cleanup evidence.

Constraint: Cleanup evidence must be recorded after PR merge and ref cleanup are real.

Rejected: Leave cleanup boxes unchecked | it would make the merged task artifact understate completion.

Confidence: high

Scope-risk: narrow

Directive: Do not mark cleanup complete without verifying PR state and branch/worktree refs.

Tested: openspec validate agent-codex-plain-gx-cockpit-welcome-2026-05-01-00-21 --type change --strict

Tested: git diff --check

Not-tested: Product code; docs-only cleanup evidence.

Co-authored-by: NagyVikt <nagy.viktordp@gmail.com>
Co-authored-by: OmX <omx@oh-my-codex.dev>

Author: 3 people

openspec/changes/agent-codex-plain-gx-cockpit-welcome-2026-05-01-00-21/tasks.md

@@ -30,5 +30,7 @@
 
 ## 5. Cleanup
 
-- [ ] 5.1 Run the finish pipeline: `gx branch finish --branch agent/codex/plain-gx-cockpit-welcome-2026-05-01-00-21 --base main --via-pr --wait-for-merge --cleanup`.
-- [ ] 5.2 Record PR URL, final `MERGED` state, and sandbox cleanup evidence.
+- [x] 5.1 Run the finish pipeline: `gx branch finish --branch agent/codex/plain-gx-cockpit-welcome-2026-05-01-00-21 --base main --via-pr --wait-for-merge --cleanup`.
+  - Evidence: PR #512 merged as https://github.com/recodeee/gitguardex/pull/512 (`MERGED`, merge commit `b9e247b5b970264252900449969142acf75ad1f7`).
+- [x] 5.2 Record PR URL, final `MERGED` state, and sandbox cleanup evidence.
+  - Evidence: original worktree `/home/deadpool/Documents/recodee/gitguardex/.omx/agent-worktrees/gitguardex__codex__plain-gx-cockpit-welcome-2026-05-01-00-21` is absent; local and remote `agent/codex/plain-gx-cockpit-welcome-2026-05-01-00-21` refs are absent; `git worktree prune` completed.