include what you use in betterRenderer

Its sources reached the standard library through the project headers they
included; those are imports now. 178 headers across 56 files, plus 18 C
library headers elsewhere for memcpy/printf and friends. MSVC's STL does
not supply these transitively the way libstdc++ does.

application/application.cpp

@@ -1,4 +1,5 @@
 module;
+#include <cstring>
 #include <cstdint>
 #include <array>
 #include <cstddef>