fix: Add package-lock.json to repository for CI/CD reproducibility

Fixed CI/CD pipeline failure by removing package-lock.json from .gitignore
and adding it to version control.

## Problem

CI/CD pipeline was failing with:
```
::error::Dependencies lock file is not found in /workspace/Weyoun/chess.
Supported file patterns: package-lock.json,npm-shrinkwrap.json,yarn.lock
```

The pipeline uses `npm ci` which requires package-lock.json for:
- Reproducible builds across environments
- Exact dependency version matching
- Faster, more reliable installations
- Security auditing consistency

## Root Cause

package-lock.json was incorrectly listed in .gitignore, preventing it from
being committed to the repository. This is a common mistake - while
node_modules/ should be ignored, package-lock.json MUST be versioned.

## Solution

1. Removed package-lock.json from .gitignore
2. Added explanatory comment about why it should be committed
3. Added package-lock.json to repository (287KB, 553 packages)

## Impact

✅ CI/CD pipeline can now run `npm ci` successfully
✅ Reproducible builds across all environments
✅ Consistent dependency versions for all developers
✅ Faster CI/CD runs (npm ci vs npm install)
✅ Better security auditing

## Best Practice

package-lock.json should ALWAYS be committed for:
- Applications (like this chess game)
- CI/CD reproducibility
- Team collaboration

It should only be excluded for:
- Libraries published to npm (so consumers control versions)

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

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

.gitignore

@@ -28,7 +28,7 @@ hive-mind-prompt-*.txt
 # Project specific
 # Dependencies
 node_modules/
-package-lock.json
+# Note: package-lock.json SHOULD be committed for reproducible builds
 
 # Testing
 coverage/