Add multi-download-client support and UI management

Implements support for configuring both qBittorrent and SABnzbd simultaneously, including migration from legacy config, protocol-aware routing, and protocol filtering. Adds new CRUD API routes for download clients, new UI management components, and updates setup and settings flows to use the new multi-client architecture. Updates documentation to describe the new structure and usage.

src/app/api/admin/settings/download-clients/test/route.ts

@@ -0,0 +1,128 @@
+/**
+ * Component: Test Download Client Connection API
+ * Documentation: documentation/phase3/download-clients.md
+ */
+
+import { NextRequest, NextResponse } from 'next/server';
+import { requireAuth, requireAdmin, AuthenticatedRequest } from '@/lib/middleware/auth';
+import { getConfigService } from '@/lib/services/config.service';
+import { getDownloadClientManager } from '@/lib/services/download-client-manager.service';
+import { DownloadClientConfig } from '@/lib/services/download-client-manager.service';
+import { RMABLogger } from '@/lib/utils/logger';
+
+const logger = RMABLogger.create('API.Admin.Settings.DownloadClients.Test');
+
+/**
+ * POST - Test download client connection
+ */
+export async function POST(request: NextRequest) {
+  return requireAuth(request, async (req: AuthenticatedRequest) => {
+    return requireAdmin(req, async () => {
+      try {
+        const body = await request.json();
+        const {
+          clientId, // Optional: existing client ID to use stored password
+          type,
+          url,
+          username,
+          password,
+          disableSSLVerify,
+          remotePathMappingEnabled,
+          remotePath,
+          localPath,
+        } = body;
+
+        // Validate type
+        if (type !== 'qbittorrent' && type !== 'sabnzbd') {
+          return NextResponse.json(
+            { error: 'Invalid client type. Must be qbittorrent or sabnzbd' },
+            { status: 400 }
+          );
+        }
+
+        const config = await getConfigService();
+        const manager = getDownloadClientManager(config);
+
+        // If editing an existing client and password not provided, use stored password
+        let effectivePassword = password;
+        let effectiveUsername = username;
+
+        if (clientId && !password) {
+          const existingClients = await manager.getAllClients();
+          const existingClient = existingClients.find(c => c.id === clientId);
+
+          if (!existingClient) {
+            return NextResponse.json(
+              { error: 'Client not found' },
+              { status: 404 }
+            );
+          }
+
+          effectivePassword = existingClient.password;
+          // Also use stored username if not provided (for qBittorrent)
+          if (!username && existingClient.username) {
+            effectiveUsername = existingClient.username;
+          }
+        }
+
+        // Validate required fields
+        if (!url || !effectivePassword) {
+          return NextResponse.json(
+            { error: 'URL and password/API key are required' },
+            { status: 400 }
+          );
+        }
+
+        if (type === 'qbittorrent' && !effectiveUsername) {
+          return NextResponse.json(
+            { error: 'Username is required for qBittorrent' },
+            { status: 400 }
+          );
+        }
+
+        // Create temporary client config for testing
+        const testConfig: DownloadClientConfig = {
+          id: 'test',
+          type,
+          name: 'Test Client',
+          enabled: true,
+          url,
+          username: effectiveUsername || undefined,
+          password: effectivePassword,
+          disableSSLVerify: disableSSLVerify || false,
+          remotePathMappingEnabled: remotePathMappingEnabled || false,
+          remotePath: remotePath || undefined,
+          localPath: localPath || undefined,
+          category: 'readmeabook',
+        };
+
+        const result = await manager.testConnection(testConfig);
+
+        if (result.success) {
+          return NextResponse.json({
+            success: true,
+            message: result.message,
+          });
+        } else {
+          return NextResponse.json(
+            {
+              success: false,
+              error: result.message,
+            },
+            { status: 400 }
+          );
+        }
+      } catch (error) {
+        const message = error instanceof Error ? error.message : String(error);
+        logger.error('Connection test failed', { error: message });
+        return NextResponse.json(
+          {
+            success: false,
+            error: message,
+          },
+          { status: 400 }
+        );
+      }
+    });
+  });
+}