feat: Add configurable real IP forwarding for bare-metal clusters

Implement a new nginx.forwardRealIP configuration flag to enable/disable
real client IP extraction from X-Forwarded-For headers on bare-metal clusters.

Changes:
- Added nginx.forwardRealIP.enabled flag (default: false) to values.yaml
- Added nginx.forwardRealIP.trustedProxies list for flexible proxy IP ranges
- Updated Nginx configmap to conditionally apply real IP extraction settings
- Updated FastCGI parameters to use real IP when enabled, direct connection IP otherwise
- Updated WordPress wp-config.php to conditionally extract real IPs from headers

Configuration:
- When enabled: Extracts real client IP from X-Forwarded-For header
- When disabled: Uses direct connection IP (default Nginx behavior)
- Supports custom proxy IP ranges for CloudFlare, AWS ALB, etc.

This allows Helmchart to work seamlessly on both:
1. Bare-metal clusters with iptables load balancing
2. Cloud-managed clusters with proper IP forwarding

Version bumped to 6.9.0-a (WordPress version with implementation suffix)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Chart.yaml

@@ -2,7 +2,7 @@ apiVersion: v2
 name: wordpress-nginx
 description: WordPress with Nginx and PHP-FPM on Kubernetes
 type: application
-version: 6.9.3
+version: 6.9.3-a
 appVersion: "6.9.0"
 keywords:
   - wordpress