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/windows-sandbox-rs/src/setup_error.rs

@@ -189,15 +189,16 @@ pub fn sanitize_setup_metric_tag_value(value: &str) -> String {
 
 fn redact_home_paths(value: &str) -> String {
     let mut usernames: Vec<String> = Vec::new();
-    if let Ok(username) = std::env::var("USERNAME") {
-        if !username.trim().is_empty() {
-            usernames.push(username);
-        }
+    if let Ok(username) = std::env::var("USERNAME")
+        && !username.trim().is_empty()
+    {
+        usernames.push(username);
     }
-    if let Ok(user) = std::env::var("USER") {
-        if !user.trim().is_empty() && !usernames.iter().any(|v| v.eq_ignore_ascii_case(&user)) {
-            usernames.push(user);
-        }
+    if let Ok(user) = std::env::var("USER")
+        && !user.trim().is_empty()
+        && !usernames.iter().any(|v| v.eq_ignore_ascii_case(&user))
+    {
+        usernames.push(user);
     }
 
     redact_username_segments(value, &usernames)