fix(onnx): pass externalData to session_options when using customCache in Node.js

[s-zx]

Problem

When a model uses external data (e.g. model.onnx_data) and the user provides a customCache (which returns a Uint8Array/Response rather than a filesystem path), loading fails in Node.js with:

file_size: system cannot find the specified path: "model.onnx_data"

Root Cause

session.js only sets session_options.externalData when !IS_NODE_ENV.

In Node.js with useFSCache this is intentional — the ONNX runtime locates .onnx_data files automatically relative to the on-disk model path.

But when customCache is used the data arrives as an in-memory Uint8Array (not a file path), so the runtime has no way to discover the sidecar files on disk.

Fix

Check whether any resolved external-data entry is a {path, data} object (i.e. in-memory bytes from a custom cache). If so, pass externalData to session_options even in Node.js:

// Before
if (externalData.length > 0 && !apis.IS_NODE_ENV) {
    session_options.externalData = externalData;
}

// After
if (externalData.length > 0) {
    if (!apis.IS_NODE_ENV || externalData.some(item => typeof item !== 'string')) {
        session_options.externalData = externalData;
    }
}

Fixes #1408

[xenova]

Hi there 👋 thanks for the PR. Any reason for doing typeof item !== 'string' instead of item instanceof Uint8Array?

[s-zx]

@xenova Good call — instanceof Uint8Array is more precise. Updated in the latest commit. The intent is specifically to detect in-memory binary data from a custom cache vs. file paths (strings) from the filesystem cache.