This commit renames all shader snippet files to conform to the newly
introduced naming convention outlined in README.md.
The new naming convention uses a `prefix_name.suffix` format to clearly
indicate the purpose and target shader stage of each snippet. This
improves the overall organization and readability of the shader code,
making it easier to understand how each snippet contributes to the
shader generation process.
No functional changes were made to the shader code itself or source
code. This is purely a refactoring for clarity and maintainability.