Make webtools host port configurable via WEBTOOLS_PORT

Port 80 on the host isn't always free (e.g. another service already bound
to it), so let .env override it like the game server ports already do.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.env.example

@@ -17,6 +17,9 @@ PUBLIC_HOST=127.0.0.1
 LOGIN_PORT=29000
 CHAR_PORT=29100
 WORLD_PORT=29200
+# Web tools + admin panel (http://<host>:<this port>/). Change this if port 80
+# is already taken by something else on the host.
+WEBTOOLS_PORT=80
 
 # --- Server / channel naming -----------------------------------------------
 LOGIN_SERVER_NAME=ROSE Login