fix: add SIGHUP/SIGTERM handling, modernize PHP support and CI

Signal handling fixes:
- SignalListener: add SIGHUP/SIGTERM handling for both Swoole
  and Workerman drivers in master and worker processes
- Prevent 100% CPU when IDE terminal is closed by ensuring
  graceful shutdown on terminal hangup

PHP version support:
- Widen PHP constraint to 8.3, 8.4, 8.5
- Bump doctrine/dbal from ^2.13.1 to ^4.4
- Bump php-cs-fixer to ^3.64, phpstan to ^1.12
- Bump swoole/ide-helper to ^5.0
- Drop phpunit ^8.5 (EOL), keep ^9.0

CI updates:
- actions/checkout@v3 → @v4 (Node.js 20 deprecated)
- Bump static analysis/code style PHP from 8.1 to 8.3

src/ZM/Utils/MessageUtil.php

@@ -99,7 +99,7 @@ class MessageUtil
         return $ls;
     }
 
-    public static function getAltMessage(null|array|MessageSegment|string $message): string
+    public static function getAltMessage(array|MessageSegment|string|null $message): string
     {
         if ($message === null) {
             return '';