feat: scroll active chapter into view when chapter drawer opens

When the mini-player chapter drawer is opened, the current chapter is
now immediately scrolled into the center of the list instead of always
starting from the top. Uses a Svelte action (setIfActive) to track the
active chapter element and a $effect to call scrollIntoView on open.

ui/src/routes/+layout.svelte

@@ -33,6 +33,21 @@
 
 	// Chapter list drawer state for the mini-player
 	let chapterDrawerOpen = $state(false);
+	let activeChapterEl = $state<HTMLElement | null>(null);
+
+	function setIfActive(node: HTMLElement, isActive: boolean) {
+		if (isActive) activeChapterEl = node;
+		return {
+			update(nowActive: boolean) { if (nowActive) activeChapterEl = node; },
+			destroy() { if (activeChapterEl === node) activeChapterEl = null; }
+		};
+	}
+
+	$effect(() => {
+		if (chapterDrawerOpen && activeChapterEl) {
+			activeChapterEl.scrollIntoView({ block: 'center' });
+		}
+	});
 
 	// The single <audio> element that persists across navigations.
 	// AudioPlayer components in chapter pages control it via audioStore.
@@ -314,15 +329,6 @@
 			>
 				{m.nav_catalogue()}
 			</a>
-			<a
-				href="https://feedback.libnovel.cc"
-				target="_blank"
-				rel="noopener noreferrer"
-				class="hidden sm:block text-sm transition-colors text-(--color-muted) hover:text-(--color-text)"
-			>
-				{m.nav_feedback()}
-			</a>
-
 			<div class="ml-auto flex items-center gap-2">
 				<!-- Theme dropdown (desktop) -->
 				<div class="hidden sm:block relative">
@@ -423,6 +429,18 @@
 										{m.nav_admin_panel()}
 									</a>
 								{/if}
+								<a
+									href="https://feedback.libnovel.cc"
+									target="_blank"
+									rel="noopener noreferrer"
+									onclick={() => { userMenuOpen = false; }}
+									class="flex items-center justify-between gap-2 px-3 py-2 text-sm text-(--color-muted) hover:text-(--color-text) hover:bg-(--color-surface-3) transition-colors"
+								>
+									{m.nav_feedback()}
+									<svg class="w-3 h-3 shrink-0 opacity-50" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+										<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M10 6H6a2 2 0 00-2 2v10a2 2 0 002 2h10a2 2 0 002-2v-4M14 4h6m0 0v6m0-6L10 14" />
+									</svg>
+								</a>
 								<div class="my-1 border-t border-(--color-border)/60"></div>
 								<form method="POST" action="/logout">
 									<button type="submit" class="w-full text-left px-3 py-2 text-sm text-(--color-danger) hover:bg-(--color-surface-3) transition-colors">
@@ -503,9 +521,12 @@
 				target="_blank"
 				rel="noopener noreferrer"
 				onclick={() => (menuOpen = false)}
-				class="px-3 py-2.5 rounded-lg text-sm font-medium transition-colors text-(--color-muted) hover:bg-(--color-surface-2) hover:text-(--color-text)"
+				class="px-3 py-2.5 rounded-lg text-sm font-medium transition-colors text-(--color-muted) hover:bg-(--color-surface-2) hover:text-(--color-text) flex items-center justify-between"
 			>
-				{m.nav_feedback()} ↗
+				{m.nav_feedback()}
+				<svg class="w-3.5 h-3.5 opacity-50" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+					<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M10 6H6a2 2 0 00-2 2v10a2 2 0 002 2h10a2 2 0 002-2v-4M14 4h6m0 0v6m0-6L10 14" />
+				</svg>
 			</a>
 				<a
 					href="/profile"
@@ -678,6 +699,7 @@
 					</div>
 					{#each audioStore.chapters as ch (ch.number)}
 						<a
+							use:setIfActive={ch.number === audioStore.chapter}
 							href="/books/{audioStore.slug}/chapters/{ch.number}"
 							onclick={() => (chapterDrawerOpen = false)}
 							class="flex items-center gap-2 py-2 text-xs transition-colors hover:text-(--color-text) {ch.number === audioStore.chapter