Public web-only release: SvxPortal front-end + auth backend, install templates and INSTALL.md

Stripped from the internal repo: per-box deploy trees, Go services (nodelist/astmeta/proxy/svxdr),
deploy/sync scripts and all secrets. Config templates for nginx, PHP-FPM, Redis and tmpfiles
live in install/ with CHANGEME placeholders.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

common.js

@@ -0,0 +1,8 @@
+'use strict';
+
+// fmt2() comes from lib/fmt.js (loaded before this file).
+
+function includesTG(n, tg){
+  return Array.isArray(n?.monitoredTGs) && n.monitoredTGs.includes(tg);
+}
+