Add demo screenshot and serve instructions to README

README.md

@@ -2,6 +2,8 @@
 
 A diarization viewer for Whisper transcription output, featuring a visual "space" display of speakers and waveform-based audio navigation.
 
+![Demo Screenshot](screenshots/demo.jpg)
+
 ## Features
 
 - **Speaker visualization**: Speakers displayed as animated orbs in a starfield
@@ -14,7 +16,11 @@ A diarization viewer for Whisper transcription output, featuring a visual "space
 1. Place your audio file in `input/`
 2. Place your Whisper transcript JSON in `outputs/float32/`
 3. Generate the waveform data (see below)
-4. Open `index.html` in a browser
+4. Start a local server and open in browser:
+   ```bash
+   npx serve -p 5000
+   ```
+   Then navigate to http://localhost:5000
 
 ## Waveform Generation