[unohee]

Summary

• Log verify sandbox byte usage and live sandbox directory count on creation and cleanup.
• Sample repository worktree count, session directory size, and verify temporary-root size every five minutes.
• Move existing git execution helpers into a small module so runner.ts stays below the 1,000-line commit-hook limit.
• Keep periodic usage sampling in diskUsage.ts because it owns the filesystem measurements and avoids growing the runner orchestration module.

Test plan

• npm test -- --run src/verify/runner.test.ts (52 passed)
• npm run lint
• npm run typecheck
• git diff --check