56ba1723b9
Add event_log.rs with EventLog (capped VecDeque, monotonic ids, mark_read, snapshot/restore) and EventLogState. Register mod in main.rs. Stub Cmd::EventLog and Cmd::MarkRead arms in server.rs to keep the exhaustive match compiling; full wiring follows in Task 4. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>