[nostalgia/core] Add key event handler

src/nostalgia/core/glfw/core.cpp

@@ -74,8 +74,9 @@ uint64_t ticksMs(Context *ctx) noexcept {
 	return static_cast<uint64_t>(now - id->startTime);
 }
 
-bool buttonDown(Context*, Key) noexcept {
-	return false;
+bool buttonDown(Context *ctx, Key key) noexcept {
+	const auto id = ctx->windowerData<GlfwImplData>();
+	return (id->keysDown >> static_cast<int>(key)) & 1;
 }
 
 ox::Error shutdown(Context *ctx) noexcept {