feat(model-provider): add MiniMax provider

[octo-patch]

Summary

• Register MiniMax as an OpenAI-compatible high-level model provider.
• Document MiniMax-M3 and MiniMax-M2.7 with the global and China OpenAI-compatible and Anthropic-compatible endpoints.
• Forward custom Anthropic base URLs and verify that the SDK appends /v1/messages exactly once.

Test plan

• corepack pnpm --filter '@tarko/llm-client' build
• corepack pnpm --filter '@tarko/model-provider' test (50 tests)
• corepack pnpm --filter '@tarko/model-provider' build
• Prettier check on the changed TypeScript files
• git diff --check

Checklist

• Added or updated necessary tests (Optional).
• Updated documentation to align with changes (Optional).
• Verified no breaking changes, or prepared solutions for any occurring breaking changes (Optional).
• My change does not involve the above items.

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