Add series browsing, search, and detail UI

Introduce full support for Audible series exploration: API routes, frontend pages, components, hooks, and integrations. Key changes:

- Prisma: add Audiobook.seriesAsin for linking audiobooks to series detail pages.
- Backend: add /api/series/search and /api/series/[asin] routes that require auth; scrape Audible series data and enrich books with library availability.
- Integrations/services: add audible-series integration and update request/HTTP services to support the workflow.
- Frontend: add /series and /series/[asin] pages, new components (SeriesCard, SeriesGrid, SeriesDetailCard, SimilarSeriesRow) and wire them to a new useSeries hook; update AudiobookDetailsModal to show/link series; add Series link to Header.
- Misc: extend audiobook types with series fields and add seriesLabels to language-config for scraping.

These changes enable users to search for series, view series metadata and books, and navigate between audiobook and series detail pages.

src/app/api/series/search/route.ts

@@ -0,0 +1,57 @@
+/**
+ * Component: Series Search API Route
+ * Documentation: documentation/integrations/audible.md
+ */
+
+import { NextRequest, NextResponse } from 'next/server';
+import { getCurrentUser } from '@/lib/middleware/auth';
+import { RMABLogger } from '@/lib/utils/logger';
+import { searchForSeries } from '@/lib/integrations/audible-series';
+
+const logger = RMABLogger.create('API.Series.Search');
+
+/**
+ * GET /api/series/search?q=game+of+thrones
+ * Search for audiobook series on Audible, de-duplicate, and return enriched summaries
+ */
+export async function GET(request: NextRequest) {
+  try {
+    // Require authentication
+    const currentUser = getCurrentUser(request);
+    if (!currentUser) {
+      return NextResponse.json(
+        { error: 'Unauthorized', message: 'Authentication required' },
+        { status: 401 }
+      );
+    }
+
+    const query = request.nextUrl.searchParams.get('q');
+
+    if (!query || query.trim().length === 0) {
+      return NextResponse.json(
+        { error: 'ValidationError', message: 'Search query is required' },
+        { status: 400 }
+      );
+    }
+
+    logger.info(`Searching series: "${query}"`);
+
+    const series = await searchForSeries(query.trim());
+
+    logger.info(`Series search complete: "${query}" -> ${series.length} results`);
+
+    return NextResponse.json({
+      success: true,
+      series,
+      query: query.trim(),
+    });
+  } catch (error) {
+    logger.error('Failed to search series', {
+      error: error instanceof Error ? error.message : String(error),
+    });
+    return NextResponse.json(
+      { error: 'SearchError', message: 'Failed to search series' },
+      { status: 500 }
+    );
+  }
+}