chore: move pty and windows sandbox to Rust 2024 (#15954)

## Why

`codex-utils-pty` and `codex-windows-sandbox` were the remaining crates
in `codex-rs` that still overrode the workspace's Rust 2024 edition.
Moving them forward in a separate PR keeps the baseline edition update
isolated from the follow-on Bazel clippy workflow in #15955, while
making linting and formatting behavior consistent with the rest of the
workspace.

This PR also needs Cargo and Bazel to agree on the edition for
`codex-windows-sandbox`. Without the Bazel-side sync, the experimental
Bazel app-server builds fail once they compile `windows-sandbox-rs`.

## What changed

- switch `codex-rs/utils/pty` and `codex-rs/windows-sandbox-rs` to
`edition = "2024"`
- update `codex-utils-pty` callsites and tests to use the collapsed `if
let` form that Clippy expects under the new edition
- fix the Rust 2024 fallout in `windows-sandbox-rs`, including the
reserved `gen` identifier, `unsafe extern` requirements, and new Clippy
findings that surfaced under the edition bump
- keep the edition bump separate from a larger unsafe cleanup by
temporarily allowing `unsafe_op_in_unsafe_fn` in the Windows entrypoint
modules that now report it under Rust 2024
- update `codex-rs/windows-sandbox-rs/BUILD.bazel` to `crate_edition =
"2024"` so Bazel compiles the crate with the same edition as Cargo





---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/15954).
* #15976
* #15955
* __->__ #15954

codex-rs/utils/pty/src/tests.rs

@@ -3,6 +3,8 @@ use std::path::Path;
 
 use pretty_assertions::assert_eq;
 
+use crate::SpawnedProcess;
+use crate::TerminalSize;
 use crate::combine_output_receivers;
 #[cfg(unix)]
 use crate::pipe::spawn_process_no_stdin_with_inherited_fds;
@@ -11,18 +13,15 @@ use crate::pty::spawn_process_with_inherited_fds;
 use crate::spawn_pipe_process;
 use crate::spawn_pipe_process_no_stdin;
 use crate::spawn_pty_process;
-use crate::SpawnedProcess;
-use crate::TerminalSize;
 
 fn find_python() -> Option<String> {
     for candidate in ["python3", "python"] {
         if let Ok(output) = std::process::Command::new(candidate)
             .arg("--version")
             .output()
+            && output.status.success()
         {
-            if output.status.success() {
-                return Some(candidate.to_string());
-            }
+            return Some(candidate.to_string());
         }
     }
     None
@@ -855,8 +854,7 @@ async fn pty_spawn_with_inherited_fds_supports_resize() -> anyhow::Result<()> {
     let write_end = unsafe { std::fs::File::from_raw_fd(fds[1]) };
 
     let env_map: HashMap<String, String> = std::env::vars().collect();
-    let script =
-        "stty -echo; printf 'start:%s\\n' \"$(stty size)\"; IFS= read _line; printf 'after:%s\\n' \"$(stty size)\"";
+    let script = "stty -echo; printf 'start:%s\\n' \"$(stty size)\"; IFS= read _line; printf 'after:%s\\n' \"$(stty size)\"";
     let spawned = spawn_process_with_inherited_fds(
         "/bin/sh",
         &["-c".to_string(), script.to_string()],