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.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web-player/src/routes/login/+page.svelte

@@ -16,8 +16,7 @@
 
 	<div class="relative flex w-full max-w-4xl flex-col items-center gap-12 text-center">
 		<div class="flex items-center gap-3">
-			<span class="h-8 w-8 rounded-xl bg-[image:var(--mf-logo-grad)] shadow-[var(--mf-logo-glow)]"
-			></span>
+			<span class="h-8 w-8 rounded-xl bg-[image:var(--mf-logo-grad)]"></span>
 			<span class="font-display text-[clamp(1.5rem,3vw,2.5rem)] font-semibold tracking-tight">
 				Musify
 			</span>