Fix js_repl view_image test runtime panic

[fjord-oai]

Summary

Fixes a flaky/panicking js_repl image-path test by running it on a multi-thread Tokio runtime and tightening assertions to focus on real behavior.

Problem

js_repl_can_attach_image_via_view_image_tool in
/Users/fjord/code/codex-jsrepl-seq/codex-rs/core/src/tools/js_repl/mod.rs
can panic under single-thread test runtime with:

can call blocking only when running on the multi-threaded runtime

It also asserted a brittle user-facing text string.

Changes

1. Updated the test runtime to:
   #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
2. Removed the brittle "attached local image path" string assertion.
3. Kept the concrete side-effect assertions:
   • tool call succeeds
   • image is actually injected into pending input (InputImage with data:image/png;base64,...)

Why this is safe

This is test-only behavior. No production runtime code paths are changed.

Validation

• Ran:
  cargo test -p codex-core tools::js_repl::tests::js_repl_can_attach_image_via_view_image_tool -- --nocapture
• Result: pass

git stack

• 👉 1 Fix js_repl view_image test runtime panic #11796
• ⏳ 2 Fix js_repl in-flight tool-call waiter race #11800
• ⏳ 3 Add feature-gated js_repl polling flow #10673
• ⏳ 4 Add optional js_repl isolation and vendored Node runtime #10670