OpenCode (`opencode run --format json`) streams NDJSON events,
similar to the Gemini agent. This wires it up so users can drive
OpenCode from Telegram / Discord / Slack / etc.
- agent/opencode/opencode.go — agent struct, factory, model/mode/provider switching
- agent/opencode/session.go — subprocess lifecycle, NDJSON event → core.Event mapping
- cmd/cc-connect/main.go — register the "opencode" agent
