fix: prioritize child idle grace retries

[danyel117]

Summary

• replace an older task-block fallback timer when a live child snapshot provides an earlier idle-grace deadline
• reduce stale-child continuation recovery from the 1 second fallback to the 250 ms grace path
• regenerate the published server bundle

Why

The Publish workflow exposed runner-load sensitivity in the stale-child test even after increasing its timeout. The underlying V1 scheduler kept the older fallback timer instead of honoring the earlier deadline it had just discovered.

Validation

• affected test passed 20 consecutive runs and now completes around 280 ms locally
• bun run lint
• bun run typecheck
• bun test with CI Bun 1.4.2: 269 passed
• bun run build with Bun 1.4.2
• bun run pack:dry-run

Follow-up to Publish runs 34897129140 and 34897762123.