feat: add GitHub Copilot support (#17)

- Add .github/prompts/ui-ux-pro-max.prompt.md for Copilot
- Add 'copilot' as new AI type in CLI
- Update detect utility to recognize .github folder
- Update CLAUDE.md sync rules with .github
- Update README with Copilot installation and usage
- Bump version to 1.2.0

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

Co-authored-by: Claude <noreply@anthropic.com>

cli/src/utils/detect.ts

@@ -22,6 +22,9 @@ export function detectAIType(cwd: string = process.cwd()): DetectionResult {
   if (existsSync(join(cwd, '.agent'))) {
     detected.push('antigravity');
   }
+  if (existsSync(join(cwd, '.github'))) {
+    detected.push('copilot');
+  }
 
   // Suggest based on what's detected
   let suggested: AIType | null = null;
@@ -44,6 +47,8 @@ export function getAITypeDescription(aiType: AIType): string {
       return 'Windsurf (.windsurf/workflows/ + .shared/)';
     case 'antigravity':
       return 'Antigravity (.agent/workflows/ + .shared/)';
+    case 'copilot':
+      return 'GitHub Copilot (.github/prompts/ + .shared/)';
     case 'all':
       return 'All AI assistants';
   }