Refresh environment dates from the configured clock (#36187)

## Why

The `<current_date>` in environment context could diverge from the clock used by current-time features, especially when a host provides an external clock.

## What changed

- Read the current time from the session's time provider whenever world state is built, and render its local date in environment context.
- Use each session's own thread ID for clock reads, including guardian sessions.
- Propagate clock-read failures through turn error events and stop before model inference.

## Testing

- Cover date updates across turns and app-server requests.
- Verify guardian clock reads use the corresponding root or guardian thread ID and do not run during prewarm.
- Verify clock failures emit an error without sending an inference request.

GitOrigin-RevId: bb7f32ccc0229b7bc6f14d7356db00bcce78066d

codex-rs/core/src/compact_tests.rs

@@ -18,7 +18,12 @@ async fn process_compacted_history_with_test_session(
         .await;
     let step_context =
         crate::session::step_context::StepContext::for_test(Arc::clone(&turn_context));
-    let world_state = Arc::new(session.build_world_state_for_step(&step_context).await);
+    let world_state = Arc::new(
+        session
+            .build_world_state_for_step(&step_context)
+            .await
+            .expect("world state should build"),
+    );
     let initial_context = session
         .build_initial_context_with_world_state(&turn_context, world_state.as_ref())
         .await;