String interpolation with array access emits corrupted output

[nahime0]

Description

Double-quoted string interpolation with array access does not match PHP. The compiler accepts the source, but the generated binary emits corrupted literal-looking output instead of the interpolated value.

Minimal reproduction

<?php
$a = ['x' => 'ok'];
echo "{$a['x']}";

Steps to reproduce

1. Save as main.php.
2. Run php main.php.
3. Compile and run with elephc.

Expected behavior

PHP 8.4 prints:

ok

Actual behavior

The elephc-compiled binary prints:

{{['x']}

Environment

• elephc 0.23.5
• PHP 8.4.19
• macOS arm64
• reproduced on 2026-06-05

Notes

This looks like interpolation parsing/lowering is preserving fragments of the template syntax instead of evaluating the embedded array access expression.