feat(provider): add MiniMax M2.1 for SiliconFlow

[jsdtxm]

This PR adds the MiniMax M2.1 model for the SiliconFlow provider.

[jsdtxm]

The siliconflow-cn registry does not provide the model MiniMaxAI/MiniMax-M2.1 directly. Instead, it only hosts Pro/MiniMaxAI/MiniMax-M2.1. Therefore, we cannot use a symbolic link to point to the expected path, as the base model isn't available under the standard name in this registry.

[rekram1-node]

thx for the note