Add Crawl4AI Assistant Chrome Extension

- Created manifest.json for the Crawl4AI Assistant extension.
- Added popup HTML, CSS, and JS files for the extension interface.
- Included icons and favicon for the extension.
- Implemented functionality for schema capture and code generation.
- Updated index.md to reflect the availability of the new extension.
- Enhanced LLM Context Builder layout and styles for consistency.
- Adjusted global styles for better branding and responsiveness.

docs/md_v2/apps/crawl4ai-assistant/background/service-worker.js

@@ -0,0 +1,39 @@
+// Service worker for Crawl4AI Assistant
+
+// Handle messages from content script
+chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
+  if (message.action === 'downloadCode') {
+    try {
+      // Create a data URL for the Python code
+      const dataUrl = 'data:text/plain;charset=utf-8,' + encodeURIComponent(message.code);
+      
+      // Download the file
+      chrome.downloads.download({
+        url: dataUrl,
+        filename: message.filename || 'crawl4ai_schema.py',
+        saveAs: true
+      }, (downloadId) => {
+        if (chrome.runtime.lastError) {
+          console.error('Download failed:', chrome.runtime.lastError);
+          sendResponse({ success: false, error: chrome.runtime.lastError.message });
+        } else {
+          console.log('Download started with ID:', downloadId);
+          sendResponse({ success: true, downloadId: downloadId });
+        }
+      });
+    } catch (error) {
+      console.error('Error creating download:', error);
+      sendResponse({ success: false, error: error.message });
+    }
+    
+    return true; // Keep the message channel open for async response
+  }
+  
+  return false;
+});
+
+// Clean up on extension install/update
+chrome.runtime.onInstalled.addListener(() => {
+  // Clear any stored state
+  chrome.storage.local.clear();
+});