Add durable reverts for paginated threads (#38292)

## What changed

- Add `ThreadStore::revert_thread` to retain history before a selected turn by creating a new immutable rollout and atomically switching the thread's stored rollout path.
- Preserve the logical thread ID and session metadata across repeated reverts.
- Track every rollout owned by a thread so archive, unarchive, and delete operations handle the complete lineage and restore moved files when metadata updates fail.
- Prevent deletion when forks still reference any rollout in the thread's lineage.

## Testing

- Cover repeated reverts, compressed source rollouts, lifecycle operations over reverted histories, reference-aware deletion, and cross-process unarchive locking.

GitOrigin-RevId: 1c05a6db3d0036ee91b562263d7ca200c6a0ea71

codex-rs/thread-store/src/lib.rs

@@ -63,6 +63,7 @@ pub use types::PreparedFork;
 pub use types::ReadThreadByRolloutPathParams;
 pub use types::ReadThreadParams;
 pub use types::ResumeThreadParams;
+pub use types::RevertThreadParams;
 pub use types::SearchTextRange;
 pub use types::SearchThreadOccurrencesParams;
 pub use types::SearchThreadsParams;