Fix reviewed artifact cleanup planning and apply

[chubes4]

Summary

• make artifact-only cleanup plans inventory and paginate the same stable size-ranked candidates shown by low-level previews
• persist and revalidate reviewed artifact paths and sizes, preserve source-dirty/unpushed worktrees, and report measured reclaimed bytes
• include DB-backed artifact cleanup in the canonical safe runner and fix stored force-policy decoding so non-forced runs cannot bypass protections

Tests

• php tests/artifact-cleanup-reviewed-run.php
• php tests/artifact-cleanup-plan-output-contract.php
• php tests/workspace-safe-cleanup-orchestrator.php
• cleanup service, retention safety, disk budget, and remaining independent standalone PHP tests
• direct PHP syntax checks and git diff --check
• homeboy review --changed-since origin/main: audit and lint passed; test stage could not initialize the WP Codebox PHPUnit harness because PHPUnit\\Framework\\TestSuite was unavailable before discovery

Closes #936