[js_repl] paths for node module resolution can be specified for js_repl (#11944)

# External (non-OpenAI) Pull Request Requirements

In `js_repl` mode, module resolution currently starts from
`js_repl_kernel.js`, which is written to a per-kernel temp dir. This
effectively means that bare imports will not resolve.

This PR adds a new config option, `js_repl_node_module_dirs`, which is a
list of dirs that are used (in order) to resolve a bare import. If none
of those work, the current working directory of the thread is used.

For example:
```toml
js_repl_node_module_dirs = [
    "/path/to/node_modules/",
    "/other/path/to/node_modules/",
]
```

codex-rs/core/src/config/profile.rs

@@ -30,9 +30,11 @@ pub struct ConfigProfile {
     pub chatgpt_base_url: Option<String>,
     /// Optional path to a file containing model instructions.
     pub model_instructions_file: Option<AbsolutePathBuf>,
+    pub js_repl_node_path: Option<AbsolutePathBuf>,
+    /// Ordered list of directories to search for Node modules in `js_repl`.
+    pub js_repl_node_module_dirs: Option<Vec<AbsolutePathBuf>>,
     /// Optional absolute path to patched zsh used by zsh-exec-bridge-backed shell execution.
     pub zsh_path: Option<AbsolutePathBuf>,
-    pub js_repl_node_path: Option<AbsolutePathBuf>,
     /// Deprecated: ignored. Use `model_instructions_file`.
     #[schemars(skip)]
     pub experimental_instructions_file: Option<AbsolutePathBuf>,