Complete the Feishu guide with publish/test steps, architecture diagram, configuration constants, CLI reference, and troubleshooting for common issues (webhook, token, group chat).
Cover webhook URL configuration, event subscription for im.message.receive_v1, build-time and runtime credential setup, and network options (direct IP, port forwarding, ngrok, cloud relay).
Initial guide covering Feishu Open Platform app creation, App ID/Secret retrieval, and required permission scopes.
