Add e-book sidecar integration and improve request handling

Introduces optional e-book sidecar downloads from Anna's Archive, including admin UI, settings API, FlareSolverr integration, and documentation. Enhances request creation logic to prevent duplicate downloads by checking for 'downloaded' and 'available' statuses, updates UI to reflect processing state, and adds SABnzbd support to download and cleanup flows. Also updates ranking algorithm documentation and improves cache invalidation for recent requests.

src/app/api/admin/settings/ebook/test-flaresolverr/route.ts

@@ -0,0 +1,45 @@
+/**
+ * Component: FlareSolverr Connection Test API
+ * Documentation: documentation/integrations/ebook-sidecar.md
+ */
+
+import { NextRequest, NextResponse } from 'next/server';
+import { requireAuth, requireAdmin, AuthenticatedRequest } from '@/lib/middleware/auth';
+import { testFlareSolverrConnection } from '@/lib/services/ebook-scraper';
+
+export async function POST(request: NextRequest) {
+  return requireAuth(request, async (req: AuthenticatedRequest) => {
+    return requireAdmin(req, async () => {
+      try {
+        const { url } = await request.json();
+
+        if (!url) {
+          return NextResponse.json(
+            { error: 'FlareSolverr URL is required' },
+            { status: 400 }
+          );
+        }
+
+        if (!url.startsWith('http')) {
+          return NextResponse.json(
+            { error: 'URL must start with http:// or https://' },
+            { status: 400 }
+          );
+        }
+
+        const result = await testFlareSolverrConnection(url);
+
+        return NextResponse.json(result);
+      } catch (error) {
+        console.error('FlareSolverr test failed:', error);
+        return NextResponse.json(
+          {
+            success: false,
+            message: error instanceof Error ? error.message : 'Unknown error',
+          },
+          { status: 500 }
+        );
+      }
+    });
+  });
+}