Add multi-layer PPI save automation

src/assets/ppi_header.h

@@ -131,6 +131,7 @@ struct PpiMinimalProjectConfig {
     std::uint32_t width = 0;
     std::uint32_t height = 0;
     std::string layer_name;
+    std::uint32_t layer_count = 1;
     std::uint32_t frame_count = 1;
     std::uint32_t frame_duration_ms = 100;
     std::span<const PpiDirtyFacePayloadConfig> dirty_faces;