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

manifest.json

@@ -0,0 +1,37 @@
+{
+  "manifest_version": 3,
+  "name": "SDB Audio Extractor",
+  "version": "1.0",
+  "description": "Extract audio from YouTube videos to your SDB soundboard",
+  "permissions": [
+    "activeTab",
+    "storage",
+    "contextMenus",
+    "notifications"
+  ],
+  "host_permissions": [
+    "https://www.youtube.com/*",
+    "http://localhost:8000/*",
+    "http://192-168-100-199.sslip.io/*"
+  ],
+  "action": {
+    "default_popup": "popup.html",
+    "default_title": "Extract Audio"
+  },
+  "content_scripts": [
+    {
+      "matches": ["https://www.youtube.com/*"],
+      "js": ["content.js"],
+      "run_at": "document_end"
+    }
+  ],
+  "background": {
+    "service_worker": "background.js"
+  },
+  "options_page": "options.html",
+  "icons": {
+    "16": "icon16.png",
+    "48": "icon48.png",
+    "128": "icon128.png"
+  }
+}