Installing for C

The ABI is behind the capi feature. Ask for the shape you want:

cargo rustc --release --features capi --crate-type staticlib  # libdaegun.a, daegun.lib
cargo rustc --release --features capi --crate-type cdylib     # libdaegun.dylib, .so, .dll

Then compile against src/c-wrapper/daegun.h. A static library needs the platform frameworks the GPU backends call into, and a shared one carries its own:

Platform	Link line
macOS, iOS	`cc app.c libdaegun.a -framework Metal -framework Foundation -framework QuartzCore`
Linux	`cc app.c libdaegun.a -lm -lpthread -ldl`
Windows	`cl app.c daegun.lib ws2_32.lib userenv.lib ntdll.lib`

Vulkan and Direct3D are opened by name at run time, so neither adds anything to link. A machine without them answers DAEGUN_UNSUPPORTED rather than failing to load.