feat: add video embed setting and processor

- Add renderVideoLinksAsEmbeds setting to UserSettings interface
- Add checkbox control in ReadingDisplaySettings component
- Create VideoEmbedProcessor component to handle video link embedding
- Integrate VideoEmbedProcessor into ContentPanel for article rendering
- Support .mp4, .webm, .ogg, .mov, .avi, .mkv, .m4v video formats
- Use ReactPlayer for embedded video playback
- Default to false (render as links)
- When enabled, video links are rendered as embedded players

src/components/Settings/ReadingDisplaySettings.tsx

@@ -72,6 +72,19 @@ const ReadingDisplaySettings: React.FC<ReadingDisplaySettingsProps> = ({ setting
         </label>
       </div>
 
+      <div className="setting-group">
+        <label htmlFor="renderVideoLinksAsEmbeds" className="checkbox-label">
+          <input
+            id="renderVideoLinksAsEmbeds"
+            type="checkbox"
+            checked={settings.renderVideoLinksAsEmbeds === true}
+            onChange={(e) => onUpdate({ renderVideoLinksAsEmbeds: e.target.checked })}
+            className="setting-checkbox"
+          />
+          <span>Render video links as embeds</span>
+        </label>
+      </div>
+
       <div className="setting-group setting-inline">
         <label>Default Highlight Visibility</label>
         <div className="highlight-level-toggles">