Lower Vulkan version requirement to 1.4.304, which should be the lowest
version supported without requiring code changes. This should also offer
out of the box support on current Linux distros, such as Debian 13 (trixie)
and Ubuntu 25.10 (questing) & 26.04 (resolute).
Also make sure that the shaderc headers are available and added to the
include path on Linux when using system libraries.
Taylor Richards
76219fd1e2