Fix thread/list cwd filtering for Windows verbatim paths (#17414)

Addresses #17302

Problem: `thread/list` compared cwd filters with raw path equality, so
`resume --last` could miss Windows sessions when the saved cwd used a
verbatim path form and the current cwd did not.

Solution: Normalize cwd comparisons through the existing path comparison
utilities before falling back to direct equality, and add Windows
regression coverage for verbatim paths. I made this a general utility
function and replaced all of the duplicated instance of it across the
code base.

codex-rs/core/src/config/service.rs

@@ -629,14 +629,7 @@ fn validate_config(value: &TomlValue) -> Result<(), toml::de::Error> {
 }
 
 fn paths_match(expected: impl AsRef<Path>, provided: impl AsRef<Path>) -> bool {
-    if let (Ok(expanded_expected), Ok(expanded_provided)) = (
-        path_utils::normalize_for_path_comparison(&expected),
-        path_utils::normalize_for_path_comparison(&provided),
-    ) {
-        expanded_expected == expanded_provided
-    } else {
-        expected.as_ref() == provided.as_ref()
-    }
+    path_utils::paths_match_after_normalization(expected, provided)
 }
 
 fn value_at_path<'a>(root: &'a TomlValue, segments: &[String]) -> Option<&'a TomlValue> {

codex-rs/core/src/tools/runtimes/mod.rs

@@ -76,14 +76,7 @@ pub(crate) fn maybe_wrap_shell_lc_with_snapshot(
         return command.to_vec();
     }
 
-    if if let (Ok(snapshot_cwd), Ok(command_cwd)) = (
-        path_utils::normalize_for_path_comparison(snapshot.cwd.as_path()),
-        path_utils::normalize_for_path_comparison(cwd),
-    ) {
-        snapshot_cwd != command_cwd
-    } else {
-        snapshot.cwd != cwd
-    } {
+    if !path_utils::paths_match_after_normalization(snapshot.cwd.as_path(), cwd) {
         return command.to_vec();
     }