This second slice of #241 adds validated conversation events and deterministic state replay on top of the Jev foundation. Events check source attribution, thread versions, and capacity before changing state. Repeated event IDs are idempotent; corrections and contribution moves retain replayable history.

Replay copies only the changed thread and, for a move, its destination. Later transitions leave earlier states unchanged while avoiding repeated copies of the full event history. A review fix clears pending settlement and scoped-choice proposals when a resolution candidate closes a thread, matching direct decision replay. This layer contains no database writes or active chat workflow.

**Review scope:** 30 files; 2,257 source lines and 1,726 test lines. Merge after the foundation PR. Decision records and interpretation are the next layers.

**Validation:** 71 focused foundation and replay tests pass on the local fix, full workspace/E2E types and repository CI pass locally. All three required GitHub checks pass on the rebased head. Tests cover replay, corrections, invalid stored state, source provenance, and capacity.


### Review fix: close pending choices