Clean orphaned runtime directories from configured TMPDIR

[chubes4]

Problem

WP Codebox leaves large runtime and test directories under the configured shared TMPDIR, but wp-codebox doctor and wp-codebox cleanup do not inventory or remove them once no recipe-run process remains.

Observed on a production coding host:

• /mnt/extrachill-workspace/tmp: approximately 35 GiB
• wp-codebox doctor --json --archive-root /mnt/extrachill-workspace/tmp --stale-after-seconds 3600: reports zero recipe-run processes and zero stale processes
• The same doctor pass checks 304 ZIPs and identifies only five invalid archives totaling roughly 5.7 MiB
• The directory contains abandoned names such as wp-codebox-release-*, wp-codebox-release-coverage-*, wp-codebox-plugin-*, wp-codebox-readonly-mounts-*, node-playground-cli-site-*, and homeboy-wp-codebox-phpunit-*
• Individual orphan directories range from hundreds of MiB to more than 2 GiB

The cleanup command therefore reports a nearly clean state while tens of GiB of WP Codebox-owned temporary runtime state remain.

Expected

wp-codebox doctor should inventory owned runtime directories under the effective temp root, classify active/leased/recent/orphaned state, and report their allocated bytes. wp-codebox cleanup should remove only safely stale orphan directories using the same ownership and liveness evidence.

Acceptance criteria

• Discover WP Codebox-owned temp directories under the effective TMPDIR, not only known archive roots.
• Protect live processes, held previews, active leases, and recently created runs.
• Age-gate stale directories with an operator-configurable threshold.
• Report candidate count, retained count/reasons, and estimated/reclaimed allocated bytes.
• Remove nested Playground, release, plugin-overlay, read-only-mount, PHPUnit, and runtime directories only when ownership and liveness are proven.
• Cleanup is idempotent and never requires operators to use raw rm or filename glob assumptions.