Add support for proxy-awareness headers: X-Forwarded-For, X-Forwarded-Port, X-Forwarded-Proto, X-Forwarded-Host, and X-Request-ID

- Updated HAProxy configuration template to set all standard proxy headers for HTTP requests.
- Added support for a unique request ID via `unique-id-format` and `unique-id-header` directives.
- Implemented E2E tests for header validation, request correlation, and configuration correctness.
- Enhanced documentation to explain usage and examples of proxy headers.
- Updated CI workflows to include E2E tests for proxy headers.

.github/workflows/build.yml

@@ -88,7 +88,7 @@ jobs:
           export PATH="$HOME/.local/bin:$PATH"
           uv run pytest tests_e2e/test_kubernetes.py -sv --tb=short
 
-  Tests-E2E-Static:
+  Tests-E2E-Additional:
     runs-on: ubuntu-latest
     needs: [Test]
     timeout-minutes: 20
@@ -107,14 +107,19 @@ jobs:
           export PATH="$HOME/.local/bin:$PATH"
           uv sync --group dev
 
-      - name: Run Docker Compose E2E tests
+      - name: Run Static E2E tests
         run: |
           export PATH="$HOME/.local/bin:$PATH"
           uv run pytest tests_e2e/test_static.py -sv --tb=short
 
+      - name: Run Proxy Headers E2E tests
+        run: |
+          export PATH="$HOME/.local/bin:$PATH"
+          uv run pytest tests_e2e/test_proxy_headers.py -sv --tb=short
+
   Build:
     runs-on: ubuntu-latest
-    needs: [Test, Tests-E2E-Docker, Tests-E2E-Kubernetes, Tests-E2E-Static]
+    needs: [Test, Tests-E2E-Docker, Tests-E2E-Kubernetes, Tests-E2E-Additional]
     permissions:
       contents: read
       packages: write