feat(php): 添加对 self 类型的支持

- 在 CompilerBase.php 中添加了对 self 类型的处理逻辑
- 将 self 类型的对象添加到对象映射中
- 添加了静态类属性读写测试用例
- 测试验证了 self 类型在静态上下文中的正确行为

src/Php/CompilerBase.php

@@ -1744,6 +1744,9 @@ class CompilerBase extends \PhpAot\Core\Translator
                 // no break
             case 'mixed':
                 return self::TYPE_VAR;
+            case 'self':
+                $this->objects[$var] = $this->classDef->getNamespacedName(false);
+                return self::TYPE_OBJECT;
             case 'resource':
                 $this->fatalError($param, 'Cannot use `resource` as a parameter type.');
                 // no break

tests/aot/static_prop_write_2.phpt

@@ -0,0 +1,21 @@
+--TEST--
+Static Class Property Read/Write Test
+--FILE--
+<?php
+class Worker
+{
+    public static ?stdClass $event = null;
+    public static string $eventLoopClass = 'Select';
+
+    public static function init() {
+        static::$eventLoopClass = static::$event ?: static::$eventLoopClass;
+        var_dump(static::$eventLoopClass);
+    }
+}
+
+function main() {
+    Worker::init();
+}
+?>
+--EXPECT--
+string(6) "Select"