test(lite): stabilize Windows subprocess exit waits

[zuohuadong]

Summary

• keep Bun Windows subprocess exit waits alive on the supported stable runtime
• reuse one scoped compatibility helper across CLI, package, standalone, and snapshot smoke processes
• verify snapshot lock release and an immediate second status invocation

Root cause

On Bun 1.3.14 for Windows, a process waiting only on Bun.Subprocess.exited can stop polling the Windows IOCP completion path before the child exit is observed (oven-sh/bun#34478). The child has already completed its work, but the harness can remain pending.

Fix

The smoke/test wait sites keep one interval reference while awaiting the subprocess result, then clear it in finally. This is test and verification infrastructure only; it does not change the Lite production CLI, dependencies, workflow timeouts, or exit semantics.

Verification

• bun run check — 88 tests passed, build, package smoke, standalone smoke
• bun x tsc --noEmit -p tsconfig.json
• git diff --check
• Windows Lite CI passed on Bun 1.3.14 (run 30751644544)

Ready for merge after final metadata review and independent verification.