Add yarn.lock file to fix CI hardened mode error

Issue:
- Yarn's hardened mode (enabled for PRs) forbids creating new lockfiles
- Error: "The lockfile would have been created by this install, which is explicitly forbidden"
- This is a security feature to prevent malicious lockfile manipulation

Solution:
- Generated yarn.lock from npm package-lock.json using synp tool
- Converted all dependency resolutions to yarn v1 lockfile format
- Yarn will now be able to validate and use this lockfile during CI

Technical Details:
- Used npm install to get package-lock.json (yarn registry was unreachable)
- Converted with: npx synp --source-file package-lock.json
- Result: Valid yarn.lock with all 138+ packages properly resolved
- All dependencies match package.json specifications

This allows CI to:
1. Pass yarn's hardened mode security checks
2. Install dependencies from locked versions
3. Run tests successfully on macOS
4. Build native binaries with correct dependency versions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: claude