[codex] add qwen3.5-4b inference example

[Fatemanx]

Summary

Add a forward-only Qwen3.5-4B inference example under example/inference/qwen3.5-4b.

What changed

• Adds infer.py, infer.sh, modeling.py, and a short README for the new example.
• Keeps only the minimal compiled entrypoints: text_prefill, text_decode, image_prefill, image_decode, and all.
• Requires MODEL_PATH from the environment; no local weight path, GPU id, or Cutlass default is baked in.
• Follows the same minimal VAE-style wrapper pattern already used by the repo's inference examples.

Validation

• python -m py_compile example/inference/qwen3.5-4b/infer.py example/inference/qwen3.5-4b/modeling.py
• bash -n example/inference/qwen3.5-4b/infer.sh
• pytest tests/example_inference/test_qwen35_4b_infer.py -q -> 6 passed

[Fatemanx]

Superseded by upstream PR SandAI-org#48