Fix Windows running thread resume path normalization (#25509)

## Why

Fixes #24944.

On Windows, app-server resume could reject an active running thread when
the requested session path used normal `C:\...` form and the
already-running path used verbatim `\\?\C:\...` form. The paths point at
the same JSONL file, but the resume stale-path guard compared raw
`PathBuf`s, so desktop resume and heartbeat flows could fail with a
mismatched-path error.

## What Changed

- Compare requested and active rollout paths with
`path_utils::paths_match_after_normalization`.
- Extend the existing running-thread mismatched-path test with a
Windows-only same-file resume case before the stale-path rejection.

## Verification

- `just test -p codex-app-server
thread_resume_rejects_mismatched_path_for_running_thread_id`

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

@@ -2766,7 +2766,7 @@ impl ThreadRequestProcessor {
                 .as_ref()
                 .or(source_thread.rollout_path.as_ref());
             if let (Some(requested_path), Some(active_path)) = (params.path.as_ref(), active_path)
-                && requested_path != active_path
+                && !path_utils::paths_match_after_normalization(requested_path, active_path)
             {
                 return Err(invalid_request(format!(
                     "cannot resume running thread {existing_thread_id} with stale path: requested `{}`, active `{}`",