Replace the old chat/sessions commands and frontend stores with direct
ACP integration. Sessions are created lazily, loaded via list_sessions
and load_session, and messages stream through the existing ACP event
pipeline.
- Add acp::create_session, list_sessions, load_session Tauri commands
- Simplify chatSessionStore to drive state from ACP responses
- Add ChatLoadingSkeleton for session loading transitions
- Add shared/api/acp.ts frontend bindings
- Remove legacy chat.rs, sessions.rs, catchup.rs, and store.rs
- Support GOOSE_LOCAL_BINARY env var for local dev
- Add tests for session loading and draft persistence
Co-authored-by: morgmart <98432065+morgmart@users.noreply.github.com>