feat(cli): integrate conductor as a built-in extension

- Introduce support for bundled 'builtin' extensions in ExtensionManager
- Migrate conductor extension to packages/core/src/extensions/builtin/conductor
- Add automatic migration logic to cleanup manual conductor installations
- Make extension versioning optional for built-ins, defaulting to CLI version
- Update build and bundle scripts to include builtin extensions
- Enhance documentation to highlight conductor as a core feature

scripts/copy_files.js

@@ -74,13 +74,21 @@ if (packageName === 'cli') {
   }
 }
 
-// Copy built-in skills for the core package.
+// Copy built-in skills and extensions for the core package.
 if (packageName === 'core') {
   const builtinSkillsSource = path.join(sourceDir, 'skills', 'builtin');
   const builtinSkillsTarget = path.join(targetDir, 'skills', 'builtin');
   if (fs.existsSync(builtinSkillsSource)) {
     fs.cpSync(builtinSkillsSource, builtinSkillsTarget, { recursive: true });
   }
+
+  const builtinExtensionsSource = path.join(sourceDir, 'extensions', 'builtin');
+  const builtinExtensionsTarget = path.join(targetDir, 'extensions', 'builtin');
+  if (fs.existsSync(builtinExtensionsSource)) {
+    fs.cpSync(builtinExtensionsSource, builtinExtensionsTarget, {
+      recursive: true,
+    });
+  }
 }
 
 console.log('Successfully copied files.');