v0.13.2

Build

• Naga WGSL validation now captures its output as a content-addressed build
  result, so unchanged shader artifacts reuse the Zig cache without rerunning
  validation or printing repeated success messages.
• Dependencies can import the new snail-shaders-vk scope to generate only
  Vulkan SPIR-V artifacts, avoiding unrelated shader targets and any Naga
  requirement.