fix: test_dns_resolution tests mock socket not subprocess

The implementation uses socket.getaddrinfo; the tests were patching
subprocess.run which had no effect, causing both tests to fail.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_network_manager.py

@@ -199,29 +199,20 @@ test2          1800    IN      CNAME   test1
         self.assertFalse(status['running'])
         self.assertIn('stats', status)
     
-    @patch('subprocess.run')
-    def test_test_dns_resolution(self, mock_run):
+    @patch('socket.getaddrinfo')
+    def test_test_dns_resolution(self, mock_getaddrinfo):
         """Test DNS resolution testing"""
-        # Mock successful DNS resolution
-        mock_run.return_value.returncode = 0
-        mock_run.return_value.stdout = 'test.cell -> 192.168.1.100'
-        mock_run.return_value.stderr = ''
-        
+        mock_getaddrinfo.return_value = [(None, None, None, None, ('192.168.1.100', 0))]
         result = self.network_manager.test_dns_resolution('test.cell')
-        
         self.assertTrue(result['success'])
         self.assertIn('192.168.1.100', result['output'])
-    
-    @patch('subprocess.run')
-    def test_test_dns_resolution_failure(self, mock_run):
+
+    @patch('socket.getaddrinfo')
+    def test_test_dns_resolution_failure(self, mock_getaddrinfo):
         """Test DNS resolution testing with failure"""
-        # Mock failed DNS resolution
-        mock_run.return_value.returncode = 1
-        mock_run.return_value.stdout = ''
-        mock_run.return_value.stderr = 'NXDOMAIN'
-        
+        import socket
+        mock_getaddrinfo.side_effect = socket.gaierror('NXDOMAIN')
         result = self.network_manager.test_dns_resolution('nonexistent.cell')
-        
         self.assertFalse(result['success'])
         self.assertIn('NXDOMAIN', result['error'])