remote-tests

Remote executor tests exercise the app-server/exec-server split to ensure that agent features work in both local and remote execution environments. Remote executor tests currently require an x86_64 Linux host machine. There are two flavors: 1. Docker (Linux exec-server) 2. Wine (Windows exec-server) ## Test Fixtures Individual test cases must opt-in to being run against a remote executor. ### codex_core Use `TestCodexBuilder::build_with_auto_env()` to opt-in to remote execution in core integration tests unless the test needs more precise control over its executor. ### app-server Start the server with `TestAppServer::new_with_auto_env()` unless the test defines its own `$CODEX_HOME/environments.toml` or will define custom environments at runtime. Start threads with `TestAppServer::send_thread_start_request_with_auto_env()` if you've created the server with the `auto_env` approach. Omit `ThreadStartParams.environments` (leave it as `None`) when doing so. ## Test Skips If a test doesn't pass in a particular remote executor configuration you can skip it in just that configuration. Include a string reason for future readers when the selected skip macro supports one. Choose the skip macro by what causes the test to fail: - `skip_if_target_windows!`: Windows target behavior. - `skip_if_wine_exec!`: Wine-exec runner constraints. - `skip_if_host_windows!`: Windows host constraints. - `skip_if_remote!`: Local-only test behavior. - `skip_if_no_remote_env!`: Remote-only test...