feat: enhance UI and fix video handling

- Hide video elements in widget for improved user experience
- Update header background for better contrast
- Prevent empty image containers from rendering
- Remove unsupported video player elements
- Add onclick attribute to links for enhanced functionality
- Include Yandex.ru in target whitelist for expanded compatibility

src/assets/item.css

@@ -118,6 +118,10 @@
     display: block !important;
   }
 
+  .tgme_widget_message_video_wrap {
+    display: none;
+  }
+
   .tgme_widget_message_poll_options {
     display: block;