feat: add MiniMax as LLM provider

[octo-patch]

Summary

Add MiniMax as a new LLM bot provider for xiaogpt, following the same OpenAI-compatible pattern used by Moonshot and other providers.

• MiniMaxBot: Extends ChatGPTBot with MiniMax API base URL (https://api.minimax.io/v1) and default model MiniMax-M1
• Config: minimax_api_key field with MINIMAX_API_KEY env var support
• CLI: --use_minimax and --minimax_api_key arguments
• Docs: README usage examples, config table entry, example YAML

Usage

export MINIMAX_API_KEY=your_api_key
xiaogpt --hardware LX06 --mute_xiaoai --use_minimax

Or via config:

bot: minimax
minimax_api_key: "your_api_key"

Files changed (10 files, 388 additions)

File	Change
xiaogpt/bot/minimax_bot.py	New MiniMaxBot class
xiaogpt/bot/__init__.py	Register in BOTS dict
xiaogpt/config.py	Add minimax_api_key + validation
xiaogpt/cli.py	Add CLI args + bot choice
README.md	Add MiniMax docs
xiao_config.yaml.example	Add MiniMax config section
tests/test_minimax_bot.py	26 unit tests
tests/test_minimax_integration.py	3 integration tests
tests/conftest.py	Test dependency mocking
tests/__init__.py	Package marker

Test plan

• 26 unit tests passing (init, config, client, history, ask, stream, registry, CLI)
• 3 integration tests passing (real API calls with MINIMAX_API_KEY)