Req support for A2A and agent cards

[jkfnc]

Please add support for A2A to add agents like mcps, poll .well-know/agent.json to get its capabilities, and add support for AgentCards

Add option to add agents like MCP.

When agent needs input, it may present a web form back and chainlit can render it and ask users to fill and submit it back.

[thangchung]

While reviewing the documentation at https://github.com/dapr/dapr-agents/blob/main/quickstarts/08-data-agent-mcp-chainlit/README.md, I came across this discussion. I concur with @jkfnc that integrating the A2A protocol into Chainlit would be highly beneficial.