tests(js_repl): stabilize CI runtime test execution

[fjord-oai]

Summary

Stabilize js_repl runtime test setup in CI and move tool-facing js_repl behavior coverage into integration tests.

This is a test/CI change only. No production js_repl behavior change is intended.

Why

• Bazel test sandboxes (especially on macOS) could resolve a different node than the one installed by actions/setup-node, which caused js_repl runtime/version failures.
• js_repl runtime tests depend on platform-specific sandbox/test-harness behavior, so they need explicit gating in a base-stability commit.
• Several tests in the js_repl unit test module were actually black-box/tool-level behavior tests and fit better in the integration suite.

Changes

• Add actions/setup-node to the Bazel and Rust Tests workflows, using the exact version pinned in the repo’s Node version file.
• In Bazel (non-Windows), pass CODEX_JS_REPL_NODE_PATH=$(which node) into test env so js_repl uses the actions/setup-node runtime inside Bazel tests.
• Add a new integration test suite for js_repl tool behavior and register it in the core integration test suite module.
• Move black-box js_repl behavior tests into the integration suite (persistence/TLA, builtin tool invocation, recursive self-call rejection, process isolation, blocked builtin imports).
• Keep white-box manager/kernel tests in the js_repl unit test module.
• Gate js_repl runtime tests to run only on macOS and only when a usable Node runtime is available (skip on other platforms / missing Node in this commit).

Impact

• Reduces js_repl CI failures caused by Node resolution drift in Bazel.
• Improves test organization by separating tool-facing behavior tests from white-box manager/kernel tests.
• Keeps the base commit stable while expanding js_repl runtime coverage.

git stack

• ✅ 1 feat: update Docker image digest to reflect #12205 #12372
• 👉 2 tests(js_repl): stabilize CI runtime test execution #12407
• ⏳ 3 tests(js_repl): remove node-related skip paths from js_repl tests #12185
• ⏳ 4 Add feature-gated js_repl polling flow #10673