feat(ui): add admin Rescrape button to book detail page

Admins see a Rescrape button next to the chapter list header.
Clicking it POSTs to /api/scrape with the book's source_url,
then shows an inline status banner (queued / busy / error).
isAdmin is exposed from the server load; no new routes needed.

ui/src/routes/books/[slug]/+page.server.ts

@@ -29,6 +29,7 @@ export const load: PageServerLoad = async ({ params, locals }) => {
 	return {
 		book,
 		chapters,
-		lastChapter: progress?.chapter ?? null
+		lastChapter: progress?.chapter ?? null,
+		isAdmin: locals.user?.role === 'admin'
 	};
 };

ui/src/routes/books/[slug]/+page.svelte

@@ -21,6 +21,30 @@
 	const visibleChapters = $derived(
 		data.chapters.slice(page * PAGE_SIZE, (page + 1) * PAGE_SIZE)
 	);
+
+	// ── Admin: rescrape ───────────────────────────────────────────────────────
+	let scraping = $state(false);
+	let scrapeResult = $state<'queued' | 'busy' | 'error' | ''>('');
+
+	async function rescrape() {
+		if (scraping || !data.book.source_url) return;
+		scraping = true;
+		scrapeResult = '';
+		try {
+			const res = await fetch('/api/scrape', {
+				method: 'POST',
+				headers: { 'Content-Type': 'application/json' },
+				body: JSON.stringify({ url: data.book.source_url })
+			});
+			if (res.ok) scrapeResult = 'queued';
+			else if (res.status === 409) scrapeResult = 'busy';
+			else scrapeResult = 'error';
+		} catch {
+			scrapeResult = 'error';
+		} finally {
+			scraping = false;
+		}
+	}
 </script>
 
 <svelte:head>
@@ -86,27 +110,65 @@
 			<span class="text-zinc-500 font-normal text-sm ml-1">({data.chapters.length})</span>
 		</h2>
 
-		{#if totalPages > 1}
+		<div class="flex items-center gap-3">
-			<div class="flex gap-2 items-center text-sm">
+			{#if data.isAdmin && data.book.source_url}
 				<button
-					onclick={() => (page = Math.max(0, page - 1))}
+					onclick={rescrape}
-					disabled={page === 0}
+					disabled={scraping}
-					class="px-2 py-1 rounded bg-zinc-700 text-zinc-300 disabled:opacity-40 hover:bg-zinc-600 transition-colors"
+					class="px-3 py-1 rounded text-xs font-medium transition-colors flex items-center gap-1.5
+						{scraping
+							? 'bg-zinc-700 text-zinc-500 cursor-not-allowed'
+							: 'bg-zinc-700 text-zinc-200 hover:bg-zinc-600'}"
+					title="Re-scrape this book from source"
 				>
-					&larr;
+					{#if scraping}
+						<svg class="w-3 h-3 animate-spin" fill="none" viewBox="0 0 24 24">
+							<circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4"></circle>
+							<path class="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z"></path>
+						</svg>
+						Queuing…
+					{:else}
+						<svg class="w-3 h-3" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+							<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 4v5h.582m15.356 2A8.001 8.001 0 004.582 9m0 0H9m11 11v-5h-.581m0 0a8.003 8.003 0 01-15.357-2m15.357 2H15"/>
+						</svg>
+						Rescrape
+					{/if}
 				</button>
-				<span class="text-zinc-400">{page + 1} / {totalPages}</span>
+			{/if}
-				<button
+
-					onclick={() => (page = Math.min(totalPages - 1, page + 1))}
+			{#if totalPages > 1}
-					disabled={page === totalPages - 1}
+				<div class="flex gap-2 items-center text-sm">
-					class="px-2 py-1 rounded bg-zinc-700 text-zinc-300 disabled:opacity-40 hover:bg-zinc-600 transition-colors"
+					<button
-				>
+						onclick={() => (page = Math.max(0, page - 1))}
-					&rarr;
+						disabled={page === 0}
-				</button>
+						class="px-2 py-1 rounded bg-zinc-700 text-zinc-300 disabled:opacity-40 hover:bg-zinc-600 transition-colors"
-			</div>
+					>
-		{/if}
+						&larr;
+					</button>
+					<span class="text-zinc-400">{page + 1} / {totalPages}</span>
+					<button
+						onclick={() => (page = Math.min(totalPages - 1, page + 1))}
+						disabled={page === totalPages - 1}
+						class="px-2 py-1 rounded bg-zinc-700 text-zinc-300 disabled:opacity-40 hover:bg-zinc-600 transition-colors"
+					>
+						&rarr;
+					</button>
+				</div>
+			{/if}
+		</div>
 	</div>
 
+	{#if scrapeResult}
+		<div class="mb-3 px-3 py-2 rounded text-xs font-medium
+			{scrapeResult === 'queued' ? 'bg-green-900/40 text-green-300 border border-green-800' :
+			 scrapeResult === 'busy'   ? 'bg-amber-900/40 text-amber-300 border border-amber-800' :
+			                             'bg-red-900/40 text-red-300 border border-red-800'}">
+			{scrapeResult === 'queued' ? 'Rescrape queued — running in background.' :
+			 scrapeResult === 'busy'   ? 'Scraper is busy with another job. Try again shortly.' :
+			                             'Failed to queue rescrape. Check server logs.'}
+		</div>
+	{/if}
+
 	{#if data.chapters.length === 0}
 		<p class="text-zinc-500 text-sm">No chapters available yet.</p>
 	{:else}