Add Chrome extension for viewing git notes on GitHub

- Popup-based extension that works on GitHub commit pages
- Shows badge with note count when commits have notes
- Displays all available git notes refs in tabbed interface
- Supports cnotes format with special formatting
- Works with any public GitHub repository (no auth required)
- Includes caching to minimize API calls (60 req/hour limit)

chrome-extension/utils.js

@@ -0,0 +1,10 @@
+// Utility functions for GitHub Git Notes Viewer
+
+// Currently empty as the main functionality is in content.js and background.js
+// This file is included in the manifest for future utility functions
+
+// Placeholder for future utilities:
+// - SHA validation
+// - Markdown rendering
+// - Enhanced error handling
+// - User preferences management