fix flyout accent color fallback, stop cava when module hidden

modules/Mpris.qml

@@ -44,7 +44,7 @@ M.BarSection {
     property var _cavaBars: Array(16).fill(0)
     Process {
         id: cavaProc
-        running: root.playing
+        running: root.playing && root.visible
         command: ["sh", "-c", "cfg=$(mktemp /tmp/nova-cava-XXXXXX.conf);" + "cat > \"$cfg\" << 'CAVAEOF'\n" + "[general]\nbars=16\nframerate=30\n[output]\nmethod=raw\nraw_target=/dev/stdout\ndata_format=ascii\nascii_max_range=100\n" + "CAVAEOF\n" + "trap 'rm -f \"$cfg\"' EXIT;" + "exec cava -p \"$cfg\""]
         stdout: SplitParser {
             splitMarker: "\n"