Add tests for clipboard image functionality and mesh plane asset creation

- Implemented a comprehensive test suite for the clipboard image module, covering various functionalities including operator registration, context handling, and image processing.
- Created a new mesh plane asset with customizable parameters and integrated it into the geometry node system.
- Developed a validation script to ensure the correct behavior of the mesh plane asset, including input handling and output verification.

src/anyimage/blender_manifest.toml

@@ -14,7 +14,7 @@ wheels = ["./wheels/blendjob-0.1.13-py3-none-any.whl"]
 
 [permissions]
 network = "Access the local Job Server and download environment dependencies and model weights"
-files = "Read source images and store environment data"
+files = "Read source and clipboard images, and store environment data"
 
 [build]
 paths_exclude_pattern = [