__init__ Style for Scheduler / TokenizerManager / ModelRunner

Apply when modifying the __init__ of:

• Scheduler — python/sglang/srt/managers/scheduler.py
• TokenizerManager — python/sglang/srt/managers/tokenizer_manager.py
• ModelRunner — python/sglang/srt/model_executor/model_runner.py

Why

• Downstream forks override one piece (tokenizer, KV cache, IPC, …).
• Inline logic forces them to copy the whole __init__, which rots against upstream.
• Splitting into init_* helpers lets them override exactly what they need.
• Reference shape: TokenizerManager.__init__ in python/sglang/srt/managers/tokenizer_manager.py.

Rules