[Feature] VLM Training Examples on NPU

[HwVanICI]

Checklist

• This feature will maintain backward compatibility with the current APIs in
  areal/api/. If not, please raise a refactor issue first.

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Background

AReaL currently provides VLM training examples only for GPU devices. There is no official documentation or example demonstrating how to train VLMs on NPU (e.g., Ascend) using AReaL and vllm-ascend. This makes NPU usage harder to adopt, debug, and reproduce.

Proposed Solution

Add a new example directory:

examples/vllm_npu/

This folder will provide:

• NPU environment setup instructions
• End-to-end VLM training examples using AReaL + vLLM-ascend
• NPU-specific configuration notes and known limitations
• Sample logs or results to validate correctness

Motivation

Providing NPU examples lowers the entry barrier for NPU users, improves reproducibility, and expands AReaL’s hardware support without changing existing APIs.