fix: close pipe handles and free attribute list when conpty spawn fails

[codebytere-ant]

Summary

PtyConnect only closed handle->hIn / handle->hOut after a successful CreateProcessW. When spawn fails (e.g. ERROR_FILE_NOT_FOUND 2, ERROR_ACCESS_DISABLED_BY_POLICY 1260), the function threw before reaching those CloseHandle calls, leaking both named-pipe server handles for every failed spawn. Long-running hosts that retry spawns steadily leak kernel handles.

Separately, the heap-allocated PROC_THREAD_ATTRIBUTE_LIST buffer (attrList) was never freed on any path — success or failure — and DeleteProcThreadAttributeList was never called.

Changes

• Close hIn/hOut and null them on the CreateProcessW failure path; also null them after the existing success-path close so PtyKill can tell they are already released.
• Call DeleteProcThreadAttributeList + delete[] attrList on every PtyConnect exit (the two attribute-setup failures, the CreateProcessW failure, and success).
• Build the Napi::Error before running cleanup on failure paths so the reported GetLastError() is the real spawn error rather than a side effect of CloseHandle / DeleteProcThreadAttributeList.
• Add a defensive close of hIn/hOut in PtyKill for the case where PtyConnect was never called.

cc @deepak1556

[deepak1556]

Thanks!