fix: preserve retry turn handoff

[Safa675]

A retryable ChatGPT Web 503 can cause Codex to retry the same user instruction under a new native turn_id. The browser adapter currently rejects that replay as stale, so the task cannot resume after model capacity recovers.

This change records a process-local handoff only for retryable 503 failures emitted by this daemon, binds the exact failed user revision to a single successor turn, and clears the handoff when a fresh instruction arrives. It also adds lifecycle regressions for the accepted retry path and for rejecting a different stale instruction.

Validation:

• bun test tests/server-lifecycle.test.ts — 37/37 passed during the original verification run
• ./node_modules/.bin/tsc --noEmit — passed after reopening the execution session
• git diff --check — passed

The repository-wide verify remains blocked by pre-existing dependency audit findings in the pinned hono and js-yaml dependencies.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.