Bootstrap default thread and route to it on server welcome

- Create or reuse cwd project, create initial thread, and include bootstrap IDs in `server.welcome`
- Update web event routing to expand the project and auto-navigate from `/` to the bootstrapped thread
- Extend WebSocket welcome contract and add server/web tests for bootstrap payload handling
7276b75dd6Julius Marminge committed on 2/27/2026, 4:52:30 AMparentbb2164c
6 files changedLine totals unavailable