feat(compiler): add native class support with export annotations

- Introduce LibraryExportedNative class with #[Native] attribute
- Add LibraryHiddenNative class with #[NoExport] and #[Native] attributes
- Create stub file for native class definitions
- Implement StubNativePoint class with native annotation and basic properties
- Add length method to StubNativePoint for geometric calculations
- Enable compiler support for native class annotations

phpunit/code/compiler_api/library_exported_native.php

@@ -0,0 +1,7 @@
+<?php
+
+#[Native]
+final class LibraryExportedNative
+{
+    public int $value = 0;
+}

phpunit/code/compiler_api/library_hidden_native.php

@@ -0,0 +1,13 @@
+<?php
+
+#[NoExport]
+#[Native]
+final class LibraryHiddenNative
+{
+    public int $value = 0;
+}
+
+function library_visible_value(): int
+{
+    return 42;
+}

phpunit/code/native-class-stub.stub.php

@@ -0,0 +1,10 @@
+<?php
+
+#[Native]
+final class StubNativePoint
+{
+    public float $x = 0.0;
+    public float $y = 0.0;
+
+    public function length(): float {}
+}