Add lifecycle hooks for inter-agent messages (#55657)

## What changed

Add `MessageLifecycleContributor` hooks to capture extension state when local agent control publishes a message and notify contributors when the recipient commits it to history, before sampling.

Carry shared delivery state through submissions, input queues, and mailbox eviction with `PendingAgentMessage`. Notify consumption at most once per delivery, release captured state when consumed or abandoned, and drop pending mail outside queue locks. Preserve the serialized message format without republishing restored history.

## Testing

Extend the mailbox eviction test to verify that publication state survives eviction and retained messages are consumed before the first resumed model sample.

GitOrigin-RevId: 9a1f6832bd48ec646a3fd179485c095e8dcc72cc

codex-rs/core/src/codex_thread.rs

@@ -404,7 +404,7 @@ impl CodexThread {
         self.io
             .submit_with_trace(
                 op, trace, /*parent_turn_id*/ None, /*root_turn_id*/ None,
-                /*residency_guard*/ None,
+                /*residency_guard*/ None, /*message_delivery*/ None,
             )
             .await
     }
@@ -550,6 +550,7 @@ impl CodexThread {
                 parent_turn_id: None,
                 root_turn_id: None,
                 residency_guard: None,
+                message_delivery: None,
             })
             .await
             .map_err(|_| CodexErr::Fatal("thread session has stopped".to_string()))?;