Add BBC Radio 4, fix Monocle 24, default volume 100

- BBC Radio 4 — 320k AAC HLS via Akamai
- Monocle 24 — fix 403 on radio.monocle.com, swap to streamtheworld
- config/mpv.conf — default volume 50 -> 100

stations.csv

@@ -3,7 +3,8 @@
 #
 # === News & Talk ===
 BBC World Service                               - news,http://stream.live.vc.bbcmedia.co.uk/bbc_world_service
-Monocle 24 (London)                             - news,http://radio.monocle.com/live
+BBC Radio 4                                     - news,http://as-hls-ww-live.akamaized.net/pool_55057080/live/ww/bbc_radio_fourfm/bbc_radio_fourfm.isml/bbc_radio_fourfm-audio=320000.norewind.m3u8
+Monocle 24 (London)                             - news,https://playerservices.streamtheworld.com/api/livestream-redirect/MONOCLE_24.mp3
 NPR (National Public Radio)                     - news,https://npr-ice.streamguys1.com/live.mp3
 Bloomberg Radio (WBBR 1130 AM)                  - news,https://playerservices.streamtheworld.com/api/livestream-redirect/WBBRBOSAAC.aac
 DW English (Deutsche Welle)                     - news,https://dwamdstream102.akamaized.net/hls/live/2015525/dwstream102/index.m3u8