The mutation flow diagram and prose previously claimed multi-statement
mutations publish through a single ManifestRepo::commit. That's wrong:
each statement commits independently to a __run__<id> branch via
commit_updates; atomicity comes from the publish_run step that promotes
the run-branch into the target (fast path) or three-way merges it
(merge path).
Diagram now shows:
- begin_run forks __run__<id> from target head
- per-statement commit_updates on the run-branch (loop)
- OCC pre-check on target head
- publish_run with fast-path / merge-path branches
- terminate_run(Published)
Prose now points at runs.md for the full run lifecycle and cites the
correct entry points: mutate_with_current_actor (mutation.rs:539),
publish_run (omnigraph.rs:858).
Addresses Codex review comment on PR #64.