fix: add co-author support for unquoted git commit messages

[akramcodez]

Description

The addCoAuthorToGitCommit function failed to inject co-author attribution for unquoted commit messages like git commit -m Fix_bug, causing the feature to be silently skipped.

Solution

• Updated regex pattern to match both quoted (-m "msg") and unquoted (-m msg) formats
• Unquoted messages are wrapped in double quotes when co-author is added
• Behavior matches shell conventions (captures single word only)

Changes

• packages/core/src/tools/shell.ts: Enhanced regex + handling logic
• packages/core/src/tools/shell.test.ts: Added test for unquoted messages

Testing

git commit -m Fix_bug_unquoted  # Now works ✓
git commit -m "Quoted message"  # Still works ✓

fixes #15