Persist paginated items in the local thread store (#32289)

## What changed

- Allow the local thread store to create paginated threads while keeping them unsupported through the app-server API.
- Filter live append items using the history mode recorded with the thread's live recorder, so paginated threads persist canonical `ItemCompleted` events instead of legacy history events.

## Testing

- Add a local-store test that creates a paginated thread and verifies that a paginated item is persisted while a legacy user-message event is omitted.

GitOrigin-RevId: 83d93660afd5f0217213d4f21b5bf2a97745ff19

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

@@ -963,6 +963,12 @@ impl ThreadRequestProcessor {
             thread_source,
             environments,
         } = params;
+        if matches!(
+            history_mode,
+            Some(codex_app_server_protocol::ThreadHistoryMode::Paginated)
+        ) {
+            return Err(method_not_found("paginated_threads is not supported yet"));
+        }
         if sandbox.is_some() && permissions.is_some() {
             return Err(invalid_request(
                 "`permissions` cannot be combined with `sandbox`",