work on moving shader loading/compilation to a separate file

src/shaders/fragment.fs

@@ -0,0 +1,7 @@
+#version 330 core
+
+out vec4 frag_color;
+
+void main() {
+    frag_color = vec4(1.0f, 0.5f, 0.2f, 1.0f);
+}