Fix artifact cleanup apply command contract

[chubes4]

Summary

• Fix artifact cleanup dry-run output so apply commands point at the high-level apply path, not the preview command.
• Normalize embedded cleanup-plan artifact previews to expose preview/rerun-preview commands instead of nested apply_command fields.
• Add a contract test for the cleanup plan artifact output shape.

Fixes #802.

Tests

• php tests/artifact-cleanup-plan-output-contract.php
• php tests/worktree-disk-budget.php
• for test in tests/*.php; do php "$test" || exit 1; done
• php -l inc/Workspace/WorkspaceArtifactCleanup.php && php -l inc/Workspace/WorkspaceCleanupPlan.php && php -l inc/Cli/Commands/WorkspaceCommand.php && php -l tests/artifact-cleanup-plan-output-contract.php
• git diff --check

AI assistance

• AI assistance: Yes
• Tool(s): openai/gpt-5.5 and OpenCode
• Used for: Implementing the focused code change, adding contract coverage, running verification, and drafting this PR description.

[homeboy-ci]

Homeboy Results — data-machine-code

Lint

✅ lint — passed

ℹ️ Full options: homeboy docs commands/lint
Deep dive: homeboy lint data-machine-code --changed-since ab15060

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/28169616034

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 Save test baseline: homeboy test data-machine-code --baseline
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 ab15060

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/28169616034

Audit

✅ audit — passed

• audit — 16 finding(s)
• Total: 16 finding(s)

Deep dive: homeboy audit data-machine-code --changed-since ab15060

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/28169616034

Tooling versions

• Homeboy CLI: homeboy 0.260.1+04458ed9e1f0+d010355
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: 01fc0445
• Action: unknown@unknown