feat(cast): show cast badge and DLNA/Cast icon in AudioOutputBadges

- Add cast-aware badge that shows protocol name (DLNA/CAST/AIR)
- Show protocol-specific SVG icons in tooltip (dlna.svg, cast_audio.svg)
- Hide DAC passthrough and exclusive mode badges when casting
- Stop hardware polling when casting to avoid misleading info
- Add purple theme styling for cast badge consistent with cast UI

cpvsc

static/cast_audio.svg

@@ -0,0 +1 @@
+<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" id="mdi-cast-audio" width="24" height="24" viewBox="0 0 24 24"><path d="M2 11V13C7 13 11 17 11 22H13C13 15.9 8.1 11 2 11M20 2H10C8.9 2 8 2.9 8 4V10.5C9 11 9.9 11.7 10.7 12.4C11.6 11 13.2 10 15 10C17.8 10 20 12.2 20 15S17.8 20 15 20H14.8C14.9 20.7 15 21.3 15 22H20C21.1 22 22 21.1 22 20V4C22 2.9 21.1 2 20 2M15 8C13.9 8 13 7.1 13 6C13 4.9 13.9 4 15 4C16.1 4 17 4.9 17 6S16.1 8 15 8M15 18C14.8 18 14.5 18 14.3 17.9C13.8 16.4 13.1 15.1 12.2 13.9C12.6 12.8 13.7 11.9 15 11.9C16.7 11.9 18 13.2 18 14.9S16.7 18 15 18M2 15V17C4.8 17 7 19.2 7 22H9C9 18.1 5.9 15 2 15M2 19V22H5C5 20.3 3.7 19 2 19" /></svg>