[Fix] HunyuanImage-3.0: unify naming hunyuan_image_3 → hunyuan_image3

[TaffyOfficial]

Purpose

Fix inconsistent naming hunyuan_image_3 → hunyuan_image3 across the codebase.

The upstream HF repo (tencent/HunyuanImage-3.0-Instruct) uses hunyuan_image_3 (underscore before "3") in file names and imports, but
vllm-omni's convention omits it (e.g. glm_image, qwen2_5_omni). The main branch currently mixes both spellings: directories use
hunyuan_image_3 while registry keys, stage config filenames, and test names already use hunyuan_image3. This causes 3 runtime
crashes:

1. diffusion/models/hunyuan_image3/hunyuan_image3_transformer.py:77
2. diffusion/models/hunyuan_image3/hunyuan_image3_tokenizer.py:16
3. platforms/musa/platform.py:41

All fail with: ModuleNotFoundError: No module named 'vllm_omni.diffusion.models.hunyuan_image_3'

Changes:

• Rename diffusion/models/hunyuan_image_3/ → hunyuan_image3/
• Rename stage configs: hunyuan_image3_moe_dit.yaml → hunyuan_image3_t2i.yaml
• Delete obsolete hunyuan_image_3_moe.yaml
• Fix import path strings in registry.py, interface.py, musa/platform.py
• Update test_hunyuanimage3_text2img.py to reference renamed config

Note: NPU/MUSA platform changes are string-only path fixes. The original paths were already broken at runtime. No NPU/MUSA hardware
available for testing.

Test Plan

This is a pure rename + string fix. No new test scripts needed — the existing test_hunyuanimage3_text2img.py has been updated to
reference the renamed config path.

Verify no remaining broken references:

grep -rn "hunyuan_image_3" vllm_omni/diffusion/ vllm_omni/platforms/ vllm_omni/model_executor/stage_configs/

Test Result

$ grep -rn "hunyuan_image_3" vllm_omni/diffusion/ vllm_omni/platforms/ vllm_omni/model_executor/stage_configs/
(no output — all references unified)

- The purpose of the PR
- The test plan
- The test results

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[hsliuustc0106]

Two config files still use the old hunyuan_image_3 naming on this branch:

1. vllm_omni/model_executor/stage_configs/hunyuan_image_3_moe_2gpu.yaml
2. vllm_omni/platforms/xpu/stage_configs/hunyuan_image_3_moe.yaml

Could you rename these for consistency?

[TaffyOfficial]

@hsliuustc0106 update

[Gaohan123]

Please globaly check if other scripts and docs are also modified

[Gaohan123]

LGTM