Fix HAProxy configuration issues and add blocked backend

**Problems Fixed:**
- Remove invalid 'http-request set-status' directive (not supported in HAProxy 3.0.11)
- Replace with proper blocked backend using 'http-request return'
- Add blocked backend template for serving blocked page with 403 status

**Changes Made:**
- Create hap_blocked_backend.tpl template for blocked IPs
- Update hap_listener.tpl to use blocked-backend instead of invalid status setting
- Modify haproxy_manager.py to include blocked backend in config generation
- Add blocked_ip_page.html copying to HAProxy directory during config generation

**Technical Details:**
- HAProxy 3.0.11 doesn't support 'http-request set-status' directive
- Use 'http-request return status 403 content-type text/html file' instead
- Blocked IPs now get proper 403 status with custom HTML page
- Configuration validation should now pass without errors

**Testing:**
- HAProxy configuration validation should succeed
- Blocked IPs should see custom page with 403 status
- All existing functionality maintained

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

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

templates/hap_blocked_backend.tpl

@@ -0,0 +1,11 @@
+# Backend for blocked IPs - serves blocked page with 403 status
+backend blocked-backend
+    mode http
+    option http-server-close
+    http-request set-header X-Forwarded-Proto https if { ssl_fc }
+    http-request set-header X-Forwarded-Port %[dst_port]
+    http-request set-header X-Forwarded-For %[src]
+    http-request set-header X-Real-IP %[src]
+    
+    # Return 403 Forbidden for blocked IPs
+    http-request return status 403 content-type text/html file /etc/haproxy/blocked_ip_page.html