Fix cleanup reclaimed-byte aggregation

[chubes4]

Summary

• Read cleanup chunk task results from direct child job engine data as well as nested system task packets.
• Count artifact discovery chunks toward artifact cleanup reclaimed-byte totals.
• Avoid aggregating empty completed chunks under an unknown type.

Fixes #431

Testing

• php tests/smoke-worktree-cleanup-cli.php
• php tests/smoke-worktree-cleanup-chunks.php
• php -l inc/Cleanup/DataMachineJobCleanupRunEvidenceStore.php
• php -l tests/smoke-worktree-cleanup-cli.php
• git diff --check
• homeboy test --path /Users/chubes/Developer/data-machine-code@fix-cleanup-reclaimed-byte-aggregation --extension wordpress

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (openai/gpt-5.5)
• Used for: Implemented the targeted cleanup evidence aggregation fix and smoke test coverage; Chris remains responsible for review and merge.

[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 a9e490c

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 a9e490c

Audit

✅ audit — passed

• dead_code — 3 finding(s)
• requested_detectors — 2 finding(s)
• intra-method-duplication — 1 finding(s)
• test_coverage — 1 finding(s)
• Total: 7 finding(s)

Deep dive: homeboy audit data-machine-code --changed-since a9e490c

Tooling versions

• Homeboy CLI: homeboy 0.188.6+62f9b46
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: 79202555
• Action: unknown@unknown