Checkpoint web-player design-system refactor and backend track genre tagging

Advances the ongoing token/componentization cleanup (anchored player dock,
border-based panels instead of floating shadows, corrected light-mode
accent/gradient tokens) alongside in-progress backend support for track
genre tags.

web-player/src/lib/components/ui/NowPlaying.svelte

@@ -8,11 +8,11 @@
 	const delays = [0, 0.3, 0.6];
 </script>
 
-<div class="absolute inset-0 flex items-end justify-center gap-[3px] bg-scrim/45 pb-2.5">
+<div class="absolute inset-0 flex items-end justify-center gap-0.75 bg-scrim/45 pb-2.5">
 	{#each delays as delay (delay)}
 		<span
-			class="w-[3px] origin-bottom rounded-full bg-on-art"
-			style="height:14px; animation:equalize .9s ease-in-out {delay}s infinite; animation-play-state:{paused
+			class="h-3.5 w-0.75 origin-bottom rounded-full bg-on-art"
+			style="animation:equalize .9s ease-in-out {delay}s infinite; animation-play-state:{paused
 				? 'paused'
 				: 'running'}"
 		></span>