Harden web root, secrets and realtime auth

- .htaccess: refuse .git, .env, docker, nodejs, sdlc*, scripts, archives and
  app internals; security headers, HSTS over TLS, optional HTTPS redirect
- uploads served through app/file.php to signed-in users only
- Apache/PHP hardening config for the container (ServerTokens, expose_php)
- least-privilege DB account and APP_SECRET_KEY via docker/php/provision.php;
  SMTP passwords re-encrypted with a random IV (secret_box.php)
- Socket.IO rooms from a PHP-signed token; /emit and cron refuse empty secrets
- escape notification text; CLI guards on build scripts; no fixed demo password

app/assets/utils/module/mailer.php

@@ -72,7 +72,8 @@ class mailer{
 			"input" 	=> $input
 		]);
 
-		return openssl_decrypt(trim($input["data"]), "AES-256-CBC", $input["key"], 0, "1234567890123456" );
+		require_once __DIR__ . '/../secret_box.php';
+		return secret_decrypt((string)$input["data"], (string)$input["key"]);
 	}