test: add react-devtools-demo extension artifacts from testing session

Generated during browser_install_popular_extension testing to verify
Chrome extension functionality works correctly.

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

react-devtools-demo/hook.js

@@ -0,0 +1,51 @@
+// React DevTools Hook (Demo Version)
+console.log('⚛️ React DevTools Demo Hook loaded');
+
+// Simulate React DevTools hook detection
+(function() {
+  // Add React detection indicator
+  if (typeof window !== 'undefined') {
+    // Check if React is present
+    const hasReact = !!(
+      window.React || 
+      window.__REACT_DEVTOOLS_GLOBAL_HOOK__ ||
+      document.querySelector('[data-reactroot]') ||
+      document.querySelector('script[src*="react"]')
+    );
+    
+    if (hasReact) {
+      console.log('⚛️ React detected! DevTools would be active');
+      
+      // Add visual indicator
+      const indicator = document.createElement('div');
+      indicator.style.cssText = `
+        position: fixed;
+        top: 50px;
+        right: 10px;
+        background: #61dafb;
+        color: #20232a;
+        padding: 8px 12px;
+        border-radius: 8px;
+        font-family: monospace;
+        font-size: 12px;
+        font-weight: bold;
+        z-index: 9999;
+        box-shadow: 0 2px 8px rgba(0,0,0,0.3);
+        border: 2px solid #20232a;
+      `;
+      indicator.textContent = '⚛️ React DevTools Active';
+      indicator.id = 'react-devtools-indicator';
+      
+      // Add when DOM is ready
+      if (document.readyState === 'loading') {
+        document.addEventListener('DOMContentLoaded', () => {
+          document.body.appendChild(indicator);
+        });
+      } else {
+        document.body.appendChild(indicator);
+      }
+    } else {
+      console.log('ℹ️ No React detected on this page');
+    }
+  }
+})();