- Fix effort-proxy direction: GPT-5.5 natively supports xhigh but not max,
so map max→xhigh (was incorrectly xhigh→max)
- Add EFFORT_MAPPING.md with full mapping table for all providers:
Anthropic, GPT-5.5, DeepSeek V4, Kimi K2.6, Gemini 3.x
- Update proxy docstring and comments