web-player: app chrome (layout, navigation, player)

PlayerExtras is merged into PlayerBar, which now renders volume and
the queue button inline and uses the new Slider (a real range input
with thumb thickness controlled via CSS variables) for both the
progress bar and volume, replacing SeekBar and VolumeControl (grep
confirmed SeekBar's `compact` mode was dead code).

Sidebar and TabsBar migrate to appNavLinks(user, counts?), removing
the duplicated nav links between the two. Decision made without
blocking: Sidebar gains the gradient Logo mark it didn't have before,
for visual consistency with MobileHeader and the login screen.

PlayerDock and MobileHeader's z-index is fixed to z-(--z-sticky)
(they're fixed bars, not menus), and SegmentedControl's to
z-(--z-raised), per the plan's note B.1.5. glass-bar and
theme-transition are applied to PlayerBar (both variants), TabsBar,
Queue and Home (hero/spotlight), replacing duplicated
blur/transition styles.

Verified with npm run check (0 errors) and npm run build; smoke-tested
/login with no console errors. No authenticated visual QA (Docker
unavailable this session).

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

@@ -0,0 +1,22 @@
+<script lang="ts">
+	interface Props {
+		size?: 'sm' | 'lg';
+	}
+
+	let { size = 'sm' }: Props = $props();
+
+	const MARK: Record<'sm' | 'lg', string> = {
+		sm: 'size-5.5 rounded-lg',
+		lg: 'size-8 rounded-control'
+	};
+
+	const TEXT: Record<'sm' | 'lg', string> = {
+		sm: 'font-display text-lg font-semibold tracking-tight text-fg',
+		lg: 'font-display text-[clamp(1.5rem,3vw,2.5rem)] font-semibold tracking-tight'
+	};
+</script>
+
+<span class="flex items-center gap-3">
+	<span class="{MARK[size]} bg-[image:var(--mf-logo-grad)]"></span>
+	<span class={TEXT[size]}>Musify</span>
+</span>

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

@@ -23,7 +23,7 @@
 		<button
 			type="button"
 			onclick={() => (value = option.value)}
-			class="relative z-10 flex-1 px-4 py-1.5 text-center text-xs font-medium transition-colors {value ===
+			class="relative z-(--z-raised) flex-1 px-4 py-1.5 text-center text-xs font-medium transition-colors {value ===
 			option.value
 				? 'text-ink'
 				: 'text-muted hover:text-fg-2'}"

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

@@ -0,0 +1,62 @@
+<script lang="ts">
+	interface Props {
+		value: number;
+		max: number;
+		label: string;
+		oninput: (value: number) => void;
+		variant: 'seek' | 'volume';
+	}
+
+	let { value, max, label, oninput, variant }: Props = $props();
+
+	const percent = $derived(max > 0 ? (value / max) * 100 : 0);
+
+	function handleInput(event: Event) {
+		oninput(Number((event.currentTarget as HTMLInputElement).value));
+	}
+</script>
+
+<input
+	type="range"
+	min="0"
+	{max}
+	{value}
+	oninput={handleInput}
+	aria-label={label}
+	class="mf-slider mf-slider-{variant}"
+	style="background:linear-gradient(to right, var(--mf-text-2) {percent}%, var(--mf-track) {percent}%)"
+/>
+
+<style>
+	.mf-slider {
+		-webkit-appearance: none;
+		appearance: none;
+		height: var(--mf-range-h);
+		border-radius: 100px;
+		outline: none;
+		cursor: pointer;
+	}
+	.mf-slider-seek {
+		width: 100%;
+	}
+	.mf-slider-volume {
+		width: var(--mf-volume-w);
+	}
+	.mf-slider::-webkit-slider-thumb {
+		-webkit-appearance: none;
+		appearance: none;
+		width: var(--mf-range-thumb);
+		height: var(--mf-range-thumb);
+		border-radius: 50%;
+		background: var(--mf-text);
+		cursor: pointer;
+	}
+	.mf-slider::-moz-range-thumb {
+		width: var(--mf-range-thumb);
+		height: var(--mf-range-thumb);
+		border-radius: 50%;
+		background: var(--mf-text);
+		border: none;
+		cursor: pointer;
+	}
+</style>