Preserve turn attribution across recovery and compaction (#51402)

## Why

Recovering an interrupted turn replaced its original trigger with `retry` and restored only its root lineage from model context. Turns suspended before that context was written could lose their attribution entirely.

## What changed

- Persist regular-turn attribution in `TurnStartedEvent` and compaction resume metadata, including the trigger, parent and root turn IDs, and initiating agent path.
- Restore matching attribution during recovery, keep unknown triggers absent, and retain the model-context root fallback for older records.
- Reconstruct attribution from surviving turns across rollback and late completion or abort events, and clear inherited attribution when spawning a forked agent.

## Testing

Add coverage for repeated cold recovery, suspension before context persistence, legacy rollouts, fresh attribution on subsequent turns, compaction checkpoints, rollback, and late terminal events.

GitOrigin-RevId: 85b5763e8fbd48a1ea2c07cfda8196e63c2cd33a

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

@@ -712,6 +712,7 @@ mod tests {
         let update = sync
             .observe_appended_items(&[RolloutItem::EventMsg(EventMsg::TurnStarted(
                 TurnStartedEvent {
+                    turn_attribution: None,
                     turn_id: "turn-1".to_string(),
                     root_turn_id: None,
                     trace_id: None,