fix: expose all required headers

CMakeLists.txt

@@ -11,7 +11,7 @@ add_library(curtle STATIC src/vector.c)
 
 target_include_directories(curtle
         PUBLIC
-        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
         $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
 )
 
@@ -28,7 +28,10 @@ install(TARGETS curtle
         INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
 )
 
-install(FILES include/curtle/curtle.h DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+install(
+        DIRECTORY include/
+        DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+)
 
 install(EXPORT curtleTargets
         FILE curtleTargets.cmake

src/vector.c

@@ -1,4 +1,4 @@
-#include "curtle/vector.h"
+#include "curtle.h"
 #include <math.h>
 
 struct vec2 vec2_add(const struct vec2 a, const struct vec2 b)