Add SDB Audio Extractor extension with options and popup UI

- Implemented manifest.json for extension configuration
- Created options.html and options.js for user settings management
- Developed popup.html and popup.js for audio extraction functionality
- Added icons for the extension (icon16.png, icon48.png)
- Integrated API token and base URL configuration with validation
- Implemented audio extraction from YouTube videos with error handling

content.js

@@ -0,0 +1,58 @@
+// Content script for YouTube pages
+(function() {
+  'use strict';
+
+  // Function to get video information
+  function getVideoInfo() {
+    const titleElement = document.querySelector('h1.ytd-watch-metadata yt-formatted-string') ||
+                        document.querySelector('h1.ytd-video-primary-info-renderer .title') ||
+                        document.querySelector('#title h1') ||
+                        document.querySelector('h1');
+
+    const title = titleElement ? titleElement.textContent.trim() : document.title;
+    const currentUrl = window.location.href;
+    const cleanUrl = getCleanVideoUrl(currentUrl);
+
+    return {
+      title: title,
+      url: cleanUrl,
+      videoId: getVideoId(currentUrl)
+    };
+  }
+
+  // Extract video ID from URL
+  function getVideoId(url) {
+    const match = url.match(/[?&]v=([^&]+)/);
+    return match ? match[1] : null;
+  }
+
+  // Clean YouTube URL to only include the video ID
+  function getCleanVideoUrl(url) {
+    const videoId = getVideoId(url);
+    if (videoId) {
+      return `https://www.youtube.com/watch?v=${videoId}`;
+    }
+    return url; // Return original if we can't extract video ID
+  }
+
+  // Listen for messages from popup
+  chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
+    if (request.action === 'getVideoInfo') {
+      const videoInfo = getVideoInfo();
+      sendResponse(videoInfo);
+    }
+    return true; // Keep message channel open for async response
+  });
+
+  // Optional: Monitor for navigation changes on YouTube (SPA)
+  let lastUrl = location.href;
+  new MutationObserver(() => {
+    const url = location.href;
+    if (url !== lastUrl) {
+      lastUrl = url;
+      // URL changed, video info might have changed
+      console.log('YouTube navigation detected');
+    }
+  }).observe(document, { subtree: true, childList: true });
+
+})();