Adds a complete end-to-end walkthrough of the server connection CLI
commands and A2A protocol facade, verified by the UAT system with real
command outputs. Covers:
- agents server --help, connect, status, serve commands
- All output formats (rich, json, yaml, plain)
- A2A JSON-RPC 2.0 wire format (A2aRequest, A2aResponse, A2aEvent)
- A2aLocalFacade: 42 supported operations, stub mode, service wiring
- get_facade() wired to real DI container
- A2aVersionNegotiator: version negotiation and mismatch handling
- ServerConnectionConfig: validation rules
Also updates examples.json index with the new entry.
