fix: update handleHealthCheck test for environment-aware debugging

Update test expectation to include troubleshooting array in error
response details. This field was added as part of environment-aware
debugging improvements in PR #303.

The handleHealthCheck error response now includes troubleshooting
steps to help users diagnose API connectivity issues.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

tests/unit/mcp/handlers-n8n-manager.test.ts

@@ -1027,6 +1027,12 @@ describe('handlers-n8n-manager', () => {
         details: {
           apiUrl: 'https://n8n.test.com',
           hint: 'Check if n8n is running and API is enabled',
+          troubleshooting: [
+            '1. Verify n8n instance is running',
+            '2. Check N8N_API_URL is correct',
+            '3. Verify N8N_API_KEY has proper permissions',
+            '4. Run n8n_diagnostic for detailed analysis',
+          ],
         },
       });
     });