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>

auth/lib/html.php

@@ -0,0 +1,10 @@
+<?php
+declare(strict_types=1);
+// html.php — shared PHP helper for every web (dmr-web, svx-web, svxlink-web).
+// Canonical copy: callmgr2/www-mumien/auth/lib/html.php; other repos carry a COPY.
+// HTML escaping for server-rendered pages.
+
+// Escape for HTML text and attribute context (quotes included, invalid UTF-8 replaced).
+function h(?string $s): string {
+  return htmlspecialchars((string)$s, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
+}