Changes:
- Backend: _validate_folder_paths() now checks checkpoints↔unet overlap
within the same library using os.path.realpath() for symlink resolution
- Backend: set() calls _validate_folder_paths() for both folder_paths and
extra_folder_paths before writing
- Backend: extracted _normalize_path_set() helper to eliminate duplicated
normalization logic
- Frontend: inline error display with red border + error message below the
conflicting input, no save triggered
- Frontend: path normalization (strip trailing slash, lowercase) in pre-check
to reduce false negatives vs backend realpath
- Frontend: asymmetric error UX — message only on the user-edited side,
red border on the pre-existing conflict side
- CSS: has-error styles with hardcoded rgba fallback for older browsers
- i18n: checkpointUnetOverlap + checkpointUnetOverlapInline keys added to
all 10 locale files
abd06c48f4