feat: Implement shader generation for toon shader

Co-authored-by: sindharta.tanuwijaya <sindharta.tanuwijaya@unity3d.com>

Author: cursoragent

com.unity.toon-graphics-test/Editor/README_ShaderGenerator.md

@@ -0,0 +1,83 @@
+# Unity Toon Shader Generator
+
+This tool helps maintain consistency between `UnityToon.shader` and `UnityToonTessellation.shader` by using a single source of truth for shared properties.
+
+## Files
+
+- **CommonPropertiesPart.shader**: Plain text list of shared property definitions (no Shader wrapper) with original comments preserved (`Packages/com.unity.toonshader/Runtime/Shaders/Common/Parts/`)
+- **TessellationPropertiesPart.shader**: Plain text list of tessellation-only property definitions (no Shader wrapper) (`Packages/com.unity.toonshader/Runtime/Shaders/Common/Parts/`)
+- **ShaderGenerator.cs**: Unity Editor script (now located in the graphics test package) that generates the shader files from the property assets
+
+## How to Use
+
+1. **Edit Properties**:
+   - Modify the plain-text part files under `Packages/com.unity.toonshader/Runtime/Shaders/Common/Parts/`
+   - The files contain only property declarations, so standard ShaderLab property syntax applies
+
+2. **Generate Shader Files**:
+   - In Unity, choose `Toon Shader > Generate Shader Files`
+   - The tool will automatically:
+     - Replace the Properties blocks in both shader files
+     - Preserve all other shader content (HLSLINCLUDE, SubShaders, etc.)
+
+## Property File Format
+
+Each property file is plain text containing only property declarations, e.g.
+
+```
+// Comments are preserved
+[HideInInspector] _simpleUI ("SimpleUI", Int ) = 0
+[Enum(OFF, 0, ON, 1)] _isUnityToonshader("Material is touched by Unity Toon Shader", Int) = 1
+_BaseColor ("BaseColor", Color) = (1,1,1,1)
+```
+
+You can use the usual ShaderLab property syntax, including comments and blank lines. The generator indents/layers them into the target shaders automatically.
+
+## Benefits
+
+- **Single Source of Truth**: All shared properties are defined in one place
+- **Consistency**: Ensures both shader files have identical shared properties
+- **Maintainability**: Easy to add, remove, or modify properties across both shaders
+- **Preservation**: All non-Properties content and comments are preserved during generation
+- **Comment Preservation**: All original comments from the Properties blocks are maintained
+- **Traceability**: Each generated shader receives an `//Auto-generated on ...` timestamp banner at the top
+
+## Manual Generation (Alternative)
+
+If you prefer to generate shaders manually, you can run the Python helper from the repository root:
+
+```bash
+cd /workspace
+python3 generate_UnityToon.py
+```
+
+Convenience launchers are provided as `generate_UnityToon.sh` and `generate_UnityToon.bat`.
+
+## Troubleshooting
+
+- **Properties block not found**: Ensure the shader files have a valid `Properties { }` block
+- **File not found errors**: Check that the property files exist in the correct paths
+- **Generation fails**: Check the Unity Console for detailed error messages
+
+## File Structure
+
+```
+com.unity.toon-graphics-test/
+└── Editor/
+    ├── ShaderGenerator.cs          # Unity Editor script
+    ├── ShaderGeneratorTest.cs      # Editor test harness
+    └── README_ShaderGenerator.md   # This file
+
+com.unity.toonshader/Runtime/Shaders/Common/Parts/
+├── CommonPropertiesPart.shader     # Shared properties (plain text)
+└── TessellationPropertiesPart.shader # Tessellation-specific properties (plain text)
+
+com.unity.toonshader/Runtime/Integrated/Shaders/
+├── UnityToon.shader                # Generated shader (regular)
+└── UnityToonTessellation.shader    # Generated shader (tessellation)
+
+generate_UnityToon.py                 # Python generator (root)
+test_generate_UnityToon.py            # Python smoke test (root)
+test_shader_generation.cs             # .NET console smoke test (root)
+generate_UnityToon.sh / .bat          # Platform launchers for the Python generator
+```