remove new-app.sh, update docs to reference app.sh directly

tools/new-app.sh

@@ -1,13 +0,0 @@
-#!/bin/bash
-set -euo pipefail
-
-# Thin wrapper — delegates to app.sh all
-if [ -z "${1:-}" ]; then
-    echo "Usage: ./tools/new-app.sh <domain>"
-    echo "  Example: ./tools/new-app.sh example.com"
-    echo ""
-    echo "For individual steps, use: ./tools/app.sh <command> <domain>"
-    exit 1
-fi
-
-exec "$(dirname "$0")/app.sh" all "$1"