fix(desktop): copy conpty payloads file by file

[WANGZHIHAOER]

Summary

• copy Windows node-pty conpty payloads file by file in both prebuild and build/Release staging paths
• avoid the Windows EIO: Access is denied failure triggered by recursive fs.cpSync on the conpty directory
• add regression coverage for both staging layouts

Why

On Windows, recursively copying the node-pty conpty directory can fail with EIO: Access is denied, while copying the contained DLL and executable files individually succeeds. This aborts the desktop rebuild during an update even though the web build has completed.

The change reuses the existing filtered directory walker for conpty payloads only; all other build directories retain their current recursive-copy behavior.

Test plan

• npm exec vitest run apps/desktop/scripts/stage-native-deps.test.mjs apps/desktop/scripts/before-pack.test.mjs — 21/21 passed
• npm run typecheck --workspace apps/desktop
• npm run pack --workspace apps/desktop on Windows x64 — packaged successfully and produced release/win-unpacked/Hermes.exe

Full-suite note

npm test --workspace apps/desktop completed with 1,688 passing and 8 failures in unrelated POSIX relaunch/path tests and existing UI tests. The unmodified main checkout reproduced the POSIX failures and failed the same UI area even earlier during module resolution.

[alt-glitch]

This was generated by AI during triage.

Duplicate of #61832 — both fix the Windows stage-native-deps build failure by copying the node-pty conpty payloads file-by-file instead of via recursive fs.cpSync. #61832 is the earlier open canonical; #61829 is its closed twin. Flagging for a maintainer to pick one.

[WANGZHIHAOER]

Closing as a duplicate of #61832. I independently reproduced the Windows recursive fs.cpSync failure for the node-pty conpty payload and confirmed the same file-by-file staging approach. Thanks for the triage.