fix: [#10] add X-Forwarded-For header to nginx HTTP config

- Add proxy_set_header X-Forwarded-For to nginx HTTP (port 80) configuration
- Enables HTTP tracker functionality through reverse proxy
- Fix resolves tracker client connection issues when using proxy
- Update smoke testing guide to reflect working HTTP tracker via proxy
- Add comprehensive end-to-end smoke testing documentation
- Update .gitignore to exclude cloned torrust-tracker/ directory
- Add project words for documentation spelling checks

Tested:
- UDP trackers (6868, 6969): ✅ Working
- HTTP tracker via proxy (80): ✅ Working
- Health check API (80): ✅ Working
- Statistics API (80): ✅ Working
- Comprehensive tracker checker: ✅ All endpoints passing

Author: josecelano

.gitignore

@@ -4,6 +4,9 @@
 # Repository organization tool output
 repomix-output.xml
 
+# Testing dependencies (when cloned locally for smoke testing)
+torrust-tracker/
+
 # Note: This repository uses distributed .gitignore files:
 # - infrastructure/.gitignore: Infrastructure-specific files (Terraform, VMs, etc.)
 # - application/.gitignore: Application-specific files (Docker, logs, data, etc.)

application/share/container/default/config/nginx.conf

@@ -11,11 +11,13 @@ server
     location /api/
     {
             proxy_pass http://tracker:1212/api/;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
     }
 
     location /
     {
             proxy_pass http://tracker:7070;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
     }
 
     location ~ /.well-known/acme-challenge

docs/guides/integration-testing-guide.md

@@ -630,6 +630,23 @@ curl -s http://$VM_IP:1212/metrics | head -10
 
 ## Step 6: Performance and Load Testing (Optional)
 
+### Alternative: External Smoke Testing
+
+For quick external validation without infrastructure complexity, consider using
+the dedicated [Smoke Testing Guide](smoke-testing-guide.md). This approach
+uses the Torrust Tracker Client tools to test your deployment from an external
+perspective:
+
+- ✅ **Quick validation** (~5 minutes vs full integration testing)
+- ✅ **External black-box testing** using official client tools
+- ✅ **Protocol-level verification** (UDP, HTTP, API endpoints)
+- ✅ **No infrastructure knowledge required** - just test the deployed services
+- ✅ **Perfect for post-deployment validation** and sanity checks
+
+The smoke testing approach complements this integration guide by providing a
+simpler alternative when you only need to verify that the deployed tracker
+is working correctly.
+
 ### 6.1 Measure Service Response Times
 
 ```bash