Closes#47678
When using mixed sort mode in the project panel, a folder and file with
the same name but different case (e.g., `hello` folder and `Hello.txt`
file) would sort incorrectly. The file could appear between an expanded
folder and its contents.
The issue was in `compare_rel_paths_mixed`: the tie-breaker logic used
case-sensitive comparison (`a == b`) to decide directory-before-file
ordering, but `natural_sort_no_tiebreak` already considers entries equal
case-insensitively. Changed to use `eq_ignore_ascii_case` to match.
Release Notes:
- Fixed project panel mixed sort mode ordering incorrectly when a file
and folder share the same name with different casing.