Add comprehensive tests for image processing nodes and refactor node imports

- Introduced new test files for image layer, image plane, normal scale, object normal rotation, shadeless, and temporary attributes.
- Implemented tests to validate the behavior of alpha curves, depth layers, and normal scales in various rendering engines.
- Refactored import paths for node groups to align with the new directory structure.
- Added checks for temporary attribute lifetimes and ensured proper cleanup without warnings.
- Enhanced CLI commands to require the Blender group and validate the presence of generated node assets before packaging.
- Updated packaging scripts to enforce the existence of necessary assets, preventing build failures.

.gitignore

@@ -42,6 +42,7 @@ secrets.bak/
 *.blend1
 blender_assets.cats.txt~
 blendcache_*
+/src/anyimage/assets/O_AnyImage.blend
 
 # Byte-compiled / optimized / DLL files
 __pycache__/
@@ -391,4 +392,4 @@ vite.config.js.timestamp-*
 vite.config.ts.timestamp-*
 .vite/
 
-models/
+models/