docs: website/API in ping-collector since 2026-10-18; quiet the install script's port probes

scripts/install_collector.sh

@@ -82,7 +82,7 @@ env_is() { grep -q "^$1=$2\s*$" "$ENV_FILE"; }
 wait_http() { # url seconds
     local i
     for i in $(seq "$2"); do
-        curl -fsS -o /dev/null --max-time 5 "$1" && return 0
+        curl -fs -o /dev/null --max-time 5 "$1" 2>/dev/null && return 0
         sleep 1
     done
     return 1