Make dark mode more colorful and give chrome bars a full tint

Mirror the earlier light-mode pastel/colorful pass for dark mode:
boost tc()'s lightness and chroma, and richen --mf-bg/--mf-elevated/
--mf-panel-bg/--mf-bar-bg/--mf-hairline the same way, so dark mode
reads as colorful instead of near-grayscale.

Sidebar, Queue, and MobileHeader used bg-bg directly, so in dark mode
they stayed almost black regardless of hue. Add --mf-chrome-bg (an
alias to --mf-bg in light mode, a solid color-mix of --mf-hero-tint
into --mf-bg in dark mode) and switch those three to bg-chrome, so
they read as a full, solid colored bar in dark mode instead of a
fading gradient (per feedback: a whole bar, not a gradient).

Also fixes glass-bar (PlayerBar/TabsBar): it set
`background-image: var(--mf-bar-bg)`, but --mf-bar-bg is a plain
color, not a valid <image>, so the declaration was silently dropped
and these bars never actually showed their tint in either mode. Changed
to background-color.

web-player/src/lib/components/player/Queue.svelte

@@ -18,7 +18,7 @@
 {#if queuePanel.open}
 	<aside
 		transition:fly={{ x: 24, duration: 220, easing: cubicOut }}
-		class="hidden shrink-0 flex-col border-l border-hairline bg-bg px-4 pt-5 sm:flex"
+		class="hidden shrink-0 flex-col border-l border-hairline bg-chrome px-4 pt-5 sm:flex"
 		style="width:var(--mf-queue-w); padding-bottom:calc(var(--mf-player-h) + 2rem)"
 	>
 		<div class="mb-5 flex items-center justify-between">