Forward real client IPs through waitress trusted-proxy flags

The X-Forwarded-For rewrite rule alone is not enough: waitress 2+
strips forwarded headers from untrusted proxies by default, so the app
still saw 127.0.0.1 with the rule active. Trust the loopback proxy and
consume x-forwarded-for on the waitress command line; waitress then
rewrites remote_addr to the real client. Runbook gains the
allowedServerVariables unlock (500.52) and both troubleshooting rows.

deploy/windows/web.config

@@ -28,7 +28,7 @@
 
     <httpPlatform
         processPath="C:\shopdb-flask\venv\Scripts\waitress-serve.exe"
-        arguments="--port=%HTTP_PLATFORM_PORT% --host=127.0.0.1 --threads=8 wsgi:app"
+        arguments="--port=%HTTP_PLATFORM_PORT% --host=127.0.0.1 --threads=8 --trusted-proxy=127.0.0.1 --trusted-proxy-headers=x-forwarded-for wsgi:app"
         stdoutLogEnabled="true"
         stdoutLogFile="C:\shopdb-flask\logs\httpplatform"
         startupTimeLimit="120"