Adjust js_repl separator regression for latest tool output shape

Update the high-level js_repl regression to assert against the current codex.tool() return shape on latest main.

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/src/tools/js_repl/mod.rs

@@ -3327,7 +3327,7 @@ await codex.emitImage(out);
             let code = format!(
                 r#"
 const out = await codex.tool("{tool_name}", {{}});
-const text = Array.isArray(out.output) ? out.output[0]?.text : undefined;
+const text = typeof out === "string" ? out : out?.output;
 console.log(text === {literal});
 console.log(text);
 "#