Web: Full header() support in JIT/AOT (replace flag, response_code)

[PurHur]

Problem

VM header() supports 1–3 arguments via PHP's header(). JIT path rejects $argc > 1:

// ext/standard/header_.php
throw new \LogicException(
    'header() JIT only supports a single string argument in this compiler build'
);

Web apps use header('Location: /foo', true, 302) and header(..., false) for multiple headers.

Goal

Parity between VM and JIT/AOT for common header() usage.

Tasks

• Extend JitHeader / LLVM helpers for optional replace + response code
• Track sent headers in standalone runtime (prevent duplicates when replace=false)
• PHPT in test/compliance and test/real for 302 redirect pattern
• http_response_code() builtin (optional, can be separate issue)

Acceptance criteria

JIT-compiled script can send redirect and custom header lines matching VM output.

Files

• ext/standard/header_.php
• ext/standard/JitHeader.php