fix(closure): 修复箭头函数局部变量声明问题

- 在ClosureGenerator中调整局部变量声明生成逻辑
- 移除CompilerBase中重复的局部变量声明代码
- 确保箭头函数正确处理局部变量声明
- 添加测试用例验证箭头函数功能正常

src/Php/CompilerBase.php

@@ -4345,7 +4345,6 @@ class CompilerBase extends \PhpAot\Core\Translator
     {
         $cb = function () use ($expr) {
             $fnCode = $this->parseStmts($expr->stmts);
-            $fnCode = $this->genLocalVarDecl() . $fnCode;
             if (!$this->isReturnStmtInLastLine($expr->stmts)) {
                 $fnCode .= 'return ' . self::VALUE_NULL . ';' . PHP_EOL;
             }

src/Php/Generator/ClosureGenerator.php

@@ -64,7 +64,8 @@ trait ClosureGenerator
             $this->addArgument('this_', self::TYPE_OBJECT);
         }
 
-        $code .= $bodyGenCb();
+        $body = $bodyGenCb();
+        $code .= $this->genLocalVarDecl() . $body;
 
         $this->indentLevel--;
         $this->context->inClosure = false;

tests/aot/arrow_fn/004.phpt

@@ -0,0 +1,18 @@
+--TEST--
+arrow function
+--FILE--
+<?php
+function foo($obj) {
+    $fn = fn (string $add) => $obj->add(new DateInterval($add));
+    $newDate = $fn('P10D');
+    echo $newDate->format('Y-m-d') . "\n";
+}
+
+function main()
+{
+    $date = new DateTimeImmutable('2000-01-01');
+    foo($date);
+}
+?>
+--EXPECT--
+2000-01-11