feat: add MiniMax provider support

[octo-patch]

Summary

This PR adds a new agent-framework-minimax package that integrates MiniMax's Anthropic-compatible API into the Microsoft Agent Framework.

What's added

• New package python/packages/minimax/agent_framework_minimax/ with:
  • MiniMaxClient — fully-featured client (with middleware, telemetry, and function invocation)
  • RawMiniMaxClient — lightweight client without layers
• Supports models: MiniMax-M2.7 and MiniMax-M2.7-highspeed
• Uses MiniMax's Anthropic-compatible API (https://api.minimax.io/anthropic)
• Filters out Anthropic-specific parameters not supported by MiniMax (betas, top_k, service_tier, etc.)
• Unit tests and integration tests included

Usage

import asyncio
from agent_framework_minimax import MiniMaxClient
from agent_framework import Message

async def main():
    client = MiniMaxClient(model="MiniMax-M2.7")
    response = await client.get_response([Message(role="user", contents=["Hello from MiniMax!"])])
    print(response.messages[0].text)

asyncio.run(main())

Environment Variables

Variable	Required	Description
MINIMAX_API_KEY	Yes	MiniMax API key
MINIMAX_CHAT_MODEL	No	Default model
MINIMAX_BASE_URL	No	Override base URL

API Documentation

• Chat (Anthropic Compatible): https://platform.minimax.io/docs/api-reference/text-anthropic-api