feat: add MiniMax M3 prompt driver

[octo-patch]

Summary

Add a dedicated MiniMax prompt driver and tokenizer with documented regional OpenAI- and Anthropic-compatible configuration.

Changes

• Add MinimaxPromptDriver with the global API endpoint as the default and support for overriding base_url with the China API endpoint.
• Add model-specific local token counting and input/output token limits for MiniMax-M3 and MiniMax-M2.7.
• Register the driver and tokenizer in the public package exports.
• Add unit coverage for initialization, serialization, endpoint selection, token counting, and model-specific input and output token limits.
• Document global and China configuration for the OpenAI- and Anthropic-compatible APIs.

Testing

• Targeted unit tests: 10 passed
• SDK request capture for all four regional and protocol endpoint combinations
• Full unit suite: 3,630 passed, 1 skipped
• make check
• make docs

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[octo-patch]

Updated the tokenizer to use the documented context window for each supported MiniMax model and added coverage for both regional API endpoints. The full unit suite, format, lint, type, spelling, coverage, Windows, Linux, and docs checks pass.

[octo-patch]

Updated the PR to document both global and China endpoints for the OpenAI- and Anthropic-compatible configurations and clarified the tokenizer's scope. I verified all four final SDK request paths and ran the 10 targeted tests, make check, and make docs.