Allow per-turn overrides for direct-only tool namespaces (#59481)

## What changed

- Add `direct_only_tool_namespaces` to `TurnStartOptions`. Omission inherits the thread configuration; an empty list clears direct-only routing for that turn. Steering ignores the option.
- Persist explicit overrides in turn context and restore them when recovering an interrupted turn, including turns started by standalone tool output.
- Keep subsequent turns and spawned or resumed child agents on the thread's routing defaults.

## Testing

Add coverage for routing changes across turns in Responses and Responses Lite, recovery without carrying overrides into subsequent turns, and child-agent inheritance.

GitOrigin-RevId: cea1a997424572d4cd372cd15b098626904c6796

codex-rs/app-server/src/request_processors/feedback_processor.rs

@@ -850,6 +850,7 @@ mod tests {
                 item: RolloutItem::TurnContext(TurnContextItem {
                     turn_id: Some((*turn_id).to_string()),
                     root_turn_id: None,
+                    direct_only_tool_namespaces: None,
                     disabled_plugin_ids: None,
                     cwd: AbsolutePathBuf::from_absolute_path(tempdir.path())
                         .expect("absolute feedback rollout directory"),

codex-rs/app-server/src/request_processors/persisted_resume_settings_tests.rs

@@ -68,6 +68,7 @@ fn turn_context_item(
     RolloutItem::TurnContext(TurnContextItem {
         turn_id: Some(turn_id.to_string()),
         root_turn_id: None,
+        direct_only_tool_namespaces: None,
         disabled_plugin_ids: None,
         cwd: cwd(),
         approval_policy,

codex-rs/app-server/src/request_processors/turn_processor.rs

@@ -694,12 +694,12 @@ impl TurnRequestProcessor {
                     .on_start(TurnStartOptions {
                         turn_trigger: params.turn_trigger,
                         parent_turn_id: params.parent_turn_id,
-                        initiating_agent_path: None,
                         root_turn_id: params.root_turn_id,
                         final_output_json_schema: params.output_schema,
                         service_tier: params.service_tier_for_turn,
                         prompt_cache_ttl: None,
                         cyber_access_program: params.cyber_access_program.map(Into::into),
+                        ..Default::default()
                     })
                     .with_additional_context(additional_context)
                     .with_responses_metadata(params.responsesapi_client_metadata)