Fix stale clean remote-backed worktree cleanup

[chubes4]

Summary

• Treat clean worktrees with no unpushed commits and an existing remote branch as safe local cleanup candidates.
• Keep retention cleanup age-gated through the existing older_than path, while avoiding the active/no-signal promotion dance for recoverable remote-backed checkouts.
• Make active/no-signal apply branch revalidation slug-aware so report/apply agree for fix/foo versus fix-foo identities.
• Harden WP_Error helpers for smoke-test stubs that expose code/data properties instead of WordPress methods.

Fixes #601.

Testing

• php -l inc/Workspace/WorkspaceWorktreeCleanupEngine.php && php -l inc/Workspace/WorkspaceActiveNoSignalCleanup.php && php -l inc/Workspace/WorkspaceCoreUtilities.php && php -l tests/smoke-worktree-cleanup.php
• php tests/smoke-worktree-cleanup.php
• php tests/smoke-worktree-metadata-reconcile.php
• php tests/smoke-worktree-bounded-cleanup-eligible-apply.php

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (gpt-5.5)
• Used for: Implemented the cleanup policy change, updated smoke coverage, ran targeted validation, and drafted this PR description. Chris requested and reviewed the behavior direction.

[homeboy-ci]

Homeboy Results — data-machine-code

Lint

✅ lint — passed

ℹ️ Full options: homeboy docs commands/lint
ℹ️ Save lint baseline: homeboy lint data-machine-code --baseline
Deep dive: homeboy lint data-machine-code --changed-since 496aa44

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-code-lint-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-code-lint-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine-code/actions/runs/27102684466

Test

✅ test — passed

ℹ️ Auto-fix lint issues: homeboy refactor data-machine-code --from lint --write
ℹ️ Collect coverage: homeboy test data-machine-code --coverage
ℹ️ Pass args to test runner: homeboy test -- [args]
ℹ️ Full options: homeboy docs commands/test
Deep dive: homeboy test data-machine-code --changed-since 496aa44

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-code-test-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-code-test-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine-code/actions/runs/27102684466

Audit

✅ audit — passed

• audit — 19 finding(s)
• Total: 19 finding(s)

Deep dive: homeboy audit data-machine-code --changed-since 496aa44

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-code-audit-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-code-audit-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine-code/actions/runs/27102684466

Tooling versions

• Homeboy CLI: homeboy 0.222.10+fc08e9a
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: 76c2439e
• Action: unknown@unknown