Add Siliconflow Provider 1Add Siliconflow Provider 1

Initial release: add SiliconFlow as a model provider for OpenClaw.

- Provides detailed steps to configure SiliconFlow, a leading domestic AI model inference platform, as a provider using the OpenAI API-compatible protocol.

- Includes recommended free and high-performance models (Qwen3, DeepSeek, Kimi, GLM, etc.), with suggested aliases for easy switching.

- Guides through provider registration, model definition, alias configuration, fallback integration, and verification.

- Supplies practical API usage examples for querying balance and available models, as well as testing model outputs.

- Emphasizes safety checks and backup tips to ensure stable deployment.