[FEAT] 将 Agno (AgnoOS) 添加为受支持的代理提供商

Add Agno as a supported agentic framework. Agno exposes agents via the AG-UI protocol through its AgentOS interface, and there is an official TypeScript adapter package @ag-ui/agno (v0.0.3) that extends HttpAgent from @ag-ui/client.

Motivation

We heavily leverage Agno in our own stack and have seen its community growing rapidly. It's a well-designed Python framework for building multi-agent systems with built-in memory, knowledge, and reasoning. It already has first-class AG-UI support via its AGUI interface.