feat(stats): wire totalStories stat tile in reader dashboard

Manually adds totalStories to generated StatsDTO type and wires it from
readerStats into ReaderStatsStrip — resolves @Elicit: stories tile was
permanently showing "—".

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/+page.svelte

@@ -41,7 +41,7 @@ const greetingText = $derived.by(() => {
 			<ReaderStatsStrip
 				documents={data.readerStats?.totalDocuments ?? null}
 				persons={data.readerStats?.totalPersons ?? null}
-				stories={null}
+				stories={data.readerStats?.totalStories ?? null}
 			/>
 
 			{#if data.canBlogWrite}