feat: export deviceToExecutionProviders and getSupportedDevices

[TimPietrusky]

Summary

Export two device utility functions from the public API so downstream libraries can implement their own device fallback logic:

• deviceToExecutionProviders(device) — maps a device string (e.g. "auto", "cuda", "cpu") to the corresponding ONNX execution providers list. Already existed internally, just not re-exported.
• getSupportedDevices() — returns a copy of the platform-specific supportedDevices array in priority order (e.g. ["cuda", "webgpu", "cpu"] on Linux x64, ["coreml", "webgpu", "cpu"] on macOS).

Why

When device="auto" and a provider crashes hard (e.g. CUDA when libcudnn.so is missing — see #1642), downstream code needs to retry providers individually. Without access to the device list, libraries have to hardcode their own copy of the platform detection logic, which drifts when transformers.js updates.

Example usage

import { getSupportedDevices } from '@huggingface/transformers';

// Walk devices one at a time, catching provider crashes
for (const device of getSupportedDevices()) {
  try {
    model = await AutoModel.from_pretrained(modelId, { device });
    break;
  } catch (err) {
    console.warn(`device=${device} failed: ${err.message}`);
  }
}

Changes

• src/backends/onnx.js: added getSupportedDevices() function
• src/transformers.js: re-exported deviceToExecutionProviders and getSupportedDevices

Closes #1645

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.