- Introduced a new `:journal-inmemory` module implementing `:journal-api` with an in-memory backend.
- Added `InMemoryJournalStore` for concurrent append, list, and clear operations using `Mutex` and `MutableList`.
- Use cases include tests, dev mode, embedded scenarios, and client-side in-process caching.
- Integrated the module into the project setup and documented usage in `:client/README.md`.
- Added comprehensive
