[Cleanup] Replace bare print() with logger and use specific exception types

[Lidang-Jiang]

Summary

Replace 8 bare print() calls in production code with proper logger calls (5 files), and replace 2 generic raise Exception with specific exception types (2 files).

Motivation: Bare print() bypasses vLLM's logging configuration (log levels, formatters, handlers). Generic Exception prevents callers from catching specific error types.

Benchmark code and intentional file I/O print(file=f) calls are left unchanged.

Changes

Exception types (2 files)

File	Change
diffusion/diffusion_engine.py:102	raise Exception(...) → raise RuntimeError(...)
model_executor/models/cosyvoice3/utils.py:183	raise Exception(...) → raise TypeError(...)

print() → logger (5 files, 8 calls)

File	Change
diffusion/attention/backends/ring/ring_utils.py	3× print(f"ERROR...") → logger.error(...)
diffusion/models/dreamid_omni/fusion.py	2× print("Warning:...") → logger.warning(...)
diffusion/models/hunyuan_image_3/hunyuan_image_3_tokenizer.py	1× print(vars) → logger.debug(...)
diffusion/models/hunyuan_image_3/hunyuan_image_3_transformer.py	1× print(f"Skipping...") → logger.warning(...)
model_executor/models/qwen3_tts/tokenizer_25hz/vq/core_vq.py	1× print(f"VQ expire...") → logger.info(...)

All new loggers use from vllm.logger import init_logger consistent with the rest of the codebase. Lazy %s formatting is used instead of f-strings.

Test plan

• ruff check passes on all 7 modified files
• ruff format --check passes on all 7 modified files
• All pre-commit hooks pass
• No functional logic changed — only logging and exception type improvements

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