AssetManager 0.5.5.60

Reusable standard image library

Added a shared standard image library for assets and categories.
Existing images can be selected from a thumbnail gallery instead of uploading the same image repeatedly.
New standard images can be added once directly from an asset or category form.
Standard images use the persistent Docker directory ./data/image-library mounted at /app/app/static/img/library.
Standard-library images are referenced and are never deleted when an asset/category association is removed or replaced.
Duplicate upload names never overwrite existing files; a numeric suffix is added automatically.
Direct per-record uploads remain available and continue to use unique UUID file names.