add VEC3 model loader

test/coders/vec3.cpp

@@ -0,0 +1,12 @@
+#include <gtest/gtest.h>
+
+#include "coders/vec3.hpp"
+#include "files/files.hpp"
+
+TEST(VEC3, Decode) {
+    auto file = std::filesystem::u8path(
+        "../res/content/base/models/demo.vec3"
+    );
+    auto bytes = files::read_bytes_buffer(file);
+    auto model = vec3::load(file.u8string(), bytes);
+}