Change "Images folder" and "Grids folder" settings to act as base paths
that combine with specific folder settings, rather than replacing them.
- Add resolve_output_path() helper function to modules/paths.py
- Update all output path usages to use combined base + specific paths
- Update gallery API to return resolved paths with display labels
- Update gallery UI to show short labels with full path on hover
Example: If base is "C:\Database\" and specific is "outputs/text",
the resolved path becomes "C:\Database\outputs\text"
Edge cases handled:
- Empty base path: uses specific path directly (backward compatible)
- Absolute specific path: ignores base path
- Empty specific path: uses base path only
