[BUG] skill-creator crashes on Windows due to non-UTF-8 terminal encoding (GBK, Shift-JIS, etc.)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When using the skill-creator skill on Windows with a non-UTF-8 system locale (e.g., GBK/Simplified Chinese), the skill crashes with encoding errors. Two scripts are affected:

1. quick_validate.py throws UnicodeDecodeError when reading SKILL.md, because Path.read_text() uses the system default encoding (GBK) instead of UTF-8.
2. package_skill.py throws UnicodeEncodeError when printing emoji characters (📦 ✅ ❌ 🔍) to a GBK terminal.

The skill-creator is completely non-functional on non-UTF-8 Windows systems.

What Should Happen?

The skill-creator skill should run successfully on Windows regardless of the system locale encoding. Both scripts should handle UTF-8 content and emoji output correctly on GBK/Shift-JIS/Big5 terminals.

Error Messages/Logs

# Bug 1 - quick_validate.py
UnicodeDecodeError: 'gbk' codec can't decode byte 0xe2 in position ...: illegal multibyte sequence

# Bug 2 - package_skill.py
UnicodeEncodeError: 'gbk' codec can't encode character '\U0001f4e6' in position ...: illegal multibyte sequence

Steps to Reproduce

1. Use Windows with Simplified Chinese system locale (or any non-UTF-8 locale)
2. Install Claude Code desktop version and activate the skill-creator skill
3. Run skill-creator to create a new skill
4. Bug 1: quick_validate.py crashes immediately with UnicodeDecodeError when reading SKILL.md
5. Bug 2: Even if Bug 1 is fixed, package_skill.py crashes with UnicodeEncodeError when printing emoji to terminal

Note: Both bugs share the same root cause — the scripts do not account for non-UTF-8 Windows terminal encodings.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.71 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

I have documented both bugs and their fixes in detail here:
https://github.com/AntlerPotato/claude-code-skill-creator-windows-fix

Related issues in other modules (same root cause, different components):

• #29699: Unicode mojibake in Edit tool on Windows
• #22056: Chrome Native Host failure with non-ASCII Windows usernames