fix(core): add exit fallback for child process close hangs

[hgylyq]

Summary

• add a minimal exit-event fallback in packages/core/src/cross-spawn-spawner.ts
• keep the current close-first behavior in the normal case
• add a Windows regression test for grandchild stdout handle inheritance

Why

Commands such as Gradle / dotnet / hvigor can finish successfully while a daemon or grandchild process still holds inherited stdout/stderr handles open. In that case Node's close event may be delayed indefinitely even though exit has already fired, which leaves shell/task execution stuck waiting for handle.exitCode.

This patch keeps existing behavior when close arrives promptly, but falls back to the cached exit result after 2 seconds when close never arrives.

Related

• fixes the same root cause discussed in Bug: bash tool hangs on Windows when grandchild process inherits stdout pipe #24784
• also matches reports like Long-running shell commands (e.g. Gradle build) hang even after “BUILD SUCCESSFUL” #25038 and Windows: terminal tool stays in thinking state after dotnet build completes successfully #24926

Testing

• Added a Windows-only regression test for the grandchild-pipe scenario
• Local �un is not available in this environment, so I could not run �un typecheck / package tests here

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The following comment was made by an LLM, it may be inaccurate:

Found potentially related PRs:

1. fix: add exit event fallback for child process close hang on Windows #26147 - "fix: add exit event fallback for child process close hang on Windows"

   • This appears to be directly related as it addresses the same issue (exit event fallback for close hangs) on Windows

2. fix: prevent pkill hang when close event never firesFix/pkill hang #25672 - "fix: prevent pkill hang when close event never fires"

   • This addresses a related issue where the close event never fires, causing hangs with pkill

Both PRs address similar root causes related to child processes not firing close events properly. #26147 in particular seems to be a very similar fix to the current PR #28336. You may want to check if #26147 was previously closed/merged and if this is a reopened or updated version of that fix.

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