Background job state machine retains zombie entries; `--fresh` does not clear them

[mariohe0007]

Summary

The background-job state machine (used by /codex:rescue, /codex:status,
/codex:cancel) appears to retain completed/failed job entries
indefinitely. Re-invoking with --background --fresh does not clear or
recycle these zombie entries, so subsequent runs can see and act on stale
state.

Reproduction

Environment:

• Windows 10 / 11
• @openai/codex-plugin-cc 1.0.5

Steps:

1. Run a Codex rescue task to completion via
   codex:rescue --model gpt-5.5 --effort high --background.
2. Wait until it shows status: completed.
3. Start a new task with --background --fresh.
4. Run /codex:status — the previously-completed job is still listed,
   and in some cases its job id is reused or its state bleeds into the
   new run's status reporting.

Suggested fix

• Auto-GC completed / failed job entries after N minutes (e.g. 30 min).
• Have --fresh actively wipe terminal-state job entries before starting
  the new run, not just decline to resume.

Happy to clarify with logs if useful — the state files live under
~/.claude/plugins/data/codex-openai-codex/state/....