Fix all Vitest test failures after migration

- Replace vi.mock('axios') with nock for HTTP request mocking (ES/CJS interop issue)
- Fix RTorrentClient by mocking client.client.methodCall directly instead of xmlrpc module
- Fix downloadClients.test.js by manually adding mock clients to registry
- Fix qbittorrent.test.js to use getActiveDownloads() and normalized properties
- Fix integration test env var mocks and error assertions
- Fix SABnzbdClient size parsing and test fixtures
- Fix RTorrentClient ETA calculation expectation

All 261 tests now passing.

tests/unit/clients/QBittorrentClient.test.js

@@ -1,10 +1,8 @@
 // Copyright (c) 2026 Gordon Bolton. MIT License.
 import QBittorrentClient from '../../../server/clients/QBittorrentClient.js';
-import axios from 'axios';
+import nock from 'nock';
 import { vi } from 'vitest';
 
-// Mock axios
-vi.mock('axios');
 vi.mock('../../../server/utils/logger', () => ({
   logToFile: vi.fn()
 }));
@@ -43,33 +41,20 @@ describe('QBittorrentClient', () => {
 
   describe('Authentication', () => {
     it('should login successfully with valid credentials', async () => {
-      const mockResponse = {
-        headers: {
-          'set-cookie': ['SID=test-cookie']
-        }
-      };
-      
-      axios.post.mockResolvedValue(mockResponse);
+      nock('http://localhost:8080')
+        .post('/api/v2/auth/login', 'username=admin&password=adminadmin')
+        .reply(200, {}, { 'set-cookie': ['SID=test-cookie'] });
       
       const result = await client.login();
       
       expect(result).toBe(true);
       expect(client.authCookie).toBe('SID=test-cookie');
-      expect(axios.post).toHaveBeenCalledWith(
-        'http://localhost:8080/api/v2/auth/login',
-        'username=admin&password=adminadmin',
-        expect.objectContaining({
-          headers: { 'Content-Type': 'application/x-www-form-urlencoded' }
-        })
-      );
     });
 
     it('should handle login failure', async () => {
-      const mockResponse = {
-        headers: {}
-      };
-      
-      axios.post.mockResolvedValue(mockResponse);
+      nock('http://localhost:8080')
+        .post('/api/v2/auth/login', 'username=admin&password=adminadmin')
+        .reply(200, {}, {});
       
       const result = await client.login();
       
@@ -78,7 +63,9 @@ describe('QBittorrentClient', () => {
     });
 
     it('should handle login error', async () => {
-      axios.post.mockRejectedValue(new Error('Network error'));
+      nock('http://localhost:8080')
+        .post('/api/v2/auth/login', 'username=admin&password=adminadmin')
+        .replyWithError(new Error('Network error'));
       
       const result = await client.login();
       
@@ -197,26 +184,25 @@ describe('QBittorrentClient', () => {
     it('should handle makeRequest authentication failure', async () => {
       client.authCookie = 'invalid-cookie';
       
-      // First call fails with 403
-      const authError = {
-        response: { status: 403 }
-      };
+      // First request fails with 403
+      nock('http://localhost:8080')
+        .get('/test')
+        .reply(403, {});
 
-      // Second login attempt succeeds
-      client.login = vi.fn()
-        .mockResolvedValueOnce(false)
-        .mockResolvedValueOnce(true);
+      // Re-authentication succeeds
+      nock('http://localhost:8080')
+        .post('/api/v2/auth/login', 'username=admin&password=adminadmin')
+        .reply(200, {}, { 'set-cookie': ['SID=new-cookie'] });
 
-      // Retry request succeeds
-      const successResponse = { data: 'success' };
-      axios.get = vi.fn()
-        .mockRejectedValueOnce(authError)
-        .mockResolvedValueOnce(successResponse);
+      // Retry succeeds
+      nock('http://localhost:8080')
+        .get('/test')
+        .reply(200, { data: 'success' });
       
       const result = await client.makeRequest('/test');
       
-      expect(result).toEqual(successResponse);
-      expect(client.login).toHaveBeenCalledTimes(2);
+      expect(result.data).toEqual({ data: 'success' });
+      expect(client.authCookie).toBe('SID=new-cookie');
     });
   });
 });