Fix waveform visibility for high resolution images

Add draw="full" parameter to showwaves filter to fill the waveform
instead of just drawing the outline, making it visible at high resolutions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

audio_to_visualization/audio_to_visualization.py

@@ -148,7 +148,7 @@ def generate_background_color(width, height, color, opacity, duration_in_seconds
 def get_audio_waveforms(av_stream, width, height, colors, opacity):
   return (
     av_stream
-      .filter("showwaves", s="%dx%d" % (width, height), mode="cline", colors=colors, split_channels=0, rate=25, scale="sqrt")
+      .filter("showwaves", s="%dx%d" % (width, height), mode="cline", colors=colors, split_channels=0, rate=25, scale="sqrt", draw="full")
       .filter("format", "rgba")
       .filter("colorchannelmixer", aa=opacity)
   )