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/core/src/codex_thread.rs

@@ -474,16 +474,9 @@ impl CodexThread {
             trace,
             cyber_access_program,
         } = request;
-        let root_turn_id = self
-            .session
-            .reference_context_item()
-            .await
-            .filter(|context| context.turn_id.as_deref() == Some(turn_id.as_str()))
-            .and_then(|context| context.root_turn_id);
         let start_options = TurnStartOptions {
             cyber_access_program,
-            root_turn_id,
-            ..Default::default()
+            ..self.session.recovered_turn_start_options(&turn_id).await
         };
         match self
             .io