Add mpv config with EBU R128 loudness normalization

Adds config/mpv.conf with af=loudnorm filter for consistent volume
across radio stations. No more manual volume adjustment when switching.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

README.md

@@ -76,12 +76,19 @@ cp stations.csv ~/.config/pyradio/stations.csv
 # or symlink it
 ln -sf "$(pwd)/radio-stations/stations.csv" ~/.config/pyradio/stations.csv
 
+# optional: use the mpv config for volume normalization
+cp config/mpv.conf ~/.config/mpv/mpv.conf
+
 # launch
 pyradio
 ```
 
 all streams are direct (icecast, HLS, shoutcast, .pls) — no youtube, no wrappers, no auth needed.
 
+## mpv config
+
+`config/mpv.conf` includes EBU R128 loudness normalization (`af=loudnorm`) so volume stays consistent across stations. copy it to `~/.config/mpv/mpv.conf` or merge the `af=loudnorm` line into your existing config.
+
 ## license
 
 public domain. listen to good radio.