Fix NSIS packaging crash with ubcp

[mirage335]

Summary

• avoid NSIS segfault by packaging ubcp as an archive
• unpack ubcp at install time using 7zip
• fetch standalone 7zip binary during build

Testing

• ./compile.sh (fails: _generate_lean-python: command not found)

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https://chatgpt.com/codex/tasks/task_e_687b62bf77c8832c85eae0f3959bc915

[Copilot]

Pull Request Overview

This PR fixes an NSIS packaging crash related to ubcp by changing the packaging approach from direct file installation to archive-based installation. The solution involves packaging ubcp as a 7z archive, fetching the 7zip standalone binary during build time, and unpacking the archive during installation.

• Downloads standalone 7zip binary (7zr.exe) during build process if not already present
• Modifies NSIS installer to copy the 7z archive and 7zip binary instead of extracting ubcp files directly
• Adds installation-time extraction of ubcp using 7zip and cleanup of the temporary archive

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
_prog/build-special.sh	Adds logic to download standalone 7zip binary (7zr.exe) for archive extraction
_lib/nsis/ubDistBuild.nsi	Changes ubcp installation from direct file copy to archive-based extraction using 7zip

[Copilot]

The wget command lacks error handling. If the download fails, the script will continue and the subsequent NSIS installation will fail. Consider adding error checking after the wget command.

Suggested change

	'https://www.7-zip.org/a/7zr.exe'
	'https://www.7-zip.org/a/7zr.exe' || { echo "Error: Failed to download 7zr.exe"; exit 1; }