Add authors pages and requestType notifications

Introduce full authors browsing/detail feature and enhance notifications to support type-specific titles.

- Add server APIs: authors search, author detail, and author books routes (audnexus integration) that require auth and enrich results with library matches.
- Add frontend pages/components: /authors listing and /authors/[asin] detail pages; AuthorCard, AuthorGrid, AuthorDetailCard, SimilarAuthorsRow, and related skeletons.
- Add hook and integration stubs: new useAuthors hook and audnexus-authors integration; update audible service to expose audibleBaseUrl.
- Update AudiobookDetailsModal to use audibleBaseUrl and link author names to author detail pages.
- Add header navigation link to Authors.
- Notifications: extend docs and code to include requestType (audiobook|ebook), add getEventTitle/getEventMeta helpers, update queue signature and providers/processors/tests to pass/handle requestType so titles can be resolved per request type.
- Misc: job queue, processors, provider tests and notification tests updated to reflect new behavior.

This change enables browsing authors and provides type-aware notification titles without per-provider changes.

src/app/api/authors/[asin]/route.ts

@@ -0,0 +1,94 @@
+/**
+ * Component: Author Detail API Route
+ * Documentation: documentation/integrations/audible.md
+ */
+
+import { NextRequest, NextResponse } from 'next/server';
+import { getCurrentUser } from '@/lib/middleware/auth';
+import { getConfigService } from '@/lib/services/config.service';
+import { AUDIBLE_REGIONS, DEFAULT_AUDIBLE_REGION, AudibleRegion } from '@/lib/types/audible';
+import { RMABLogger } from '@/lib/utils/logger';
+import {
+  AudnexusAuthorDetail,
+  fetchAuthorDetail,
+} from '@/lib/integrations/audnexus-authors';
+
+const logger = RMABLogger.create('API.Authors.Detail');
+
+const SIMILAR_AUTHORS_LIMIT = 15;
+
+/**
+ * GET /api/authors/{asin}
+ * Fetch author detail from Audnexus with enriched similar author images
+ */
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ asin: string }> }
+) {
+  try {
+    const currentUser = getCurrentUser(request);
+    if (!currentUser) {
+      return NextResponse.json(
+        { error: 'Unauthorized', message: 'Authentication required' },
+        { status: 401 }
+      );
+    }
+
+    const { asin } = await params;
+
+    if (!asin || !/^[A-Z0-9]{10}$/.test(asin)) {
+      return NextResponse.json(
+        { error: 'ValidationError', message: 'Valid author ASIN is required' },
+        { status: 400 }
+      );
+    }
+
+    const configService = getConfigService();
+    const audibleRegion: AudibleRegion = await configService.getAudibleRegion();
+    const regionConfig = AUDIBLE_REGIONS[audibleRegion] || AUDIBLE_REGIONS[DEFAULT_AUDIBLE_REGION];
+    const region = regionConfig.audnexusParam;
+
+    logger.info(`Fetching author detail: ${asin} (region: ${region})`);
+
+    // Fetch the primary author detail
+    const detail = await fetchAuthorDetail(asin, region);
+    if (!detail) {
+      return NextResponse.json(
+        { error: 'NotFound', message: 'Author not found' },
+        { status: 404 }
+      );
+    }
+
+    // Fetch images for similar authors in parallel (capped)
+    const similarSlice = (detail.similar || []).slice(0, SIMILAR_AUTHORS_LIMIT);
+    const similarDetails = await Promise.all(
+      similarSlice.map(s => fetchAuthorDetail(s.asin, region))
+    );
+
+    const similarAuthors = similarSlice.map((s, i) => ({
+      asin: s.asin,
+      name: s.name,
+      image: similarDetails[i]?.image || undefined,
+    }));
+
+    const author = {
+      asin: detail.asin,
+      name: detail.name,
+      description: detail.description || undefined,
+      image: detail.image || undefined,
+      genres: detail.genres?.map(g => g.name) || [],
+      similar: similarAuthors,
+      audibleUrl: `${regionConfig.baseUrl}/author/${asin}`,
+    };
+
+    logger.info(`Author detail complete: "${detail.name}" (${similarAuthors.length} similar authors)`);
+
+    return NextResponse.json({ success: true, author });
+  } catch (error) {
+    logger.error('Failed to fetch author detail', { error: error instanceof Error ? error.message : String(error) });
+    return NextResponse.json(
+      { error: 'FetchError', message: 'Failed to fetch author details' },
+      { status: 500 }
+    );
+  }
+}