[Refactor] App.jsx: Distribute controllers to each files.

src-ui/app/_app_controllers/FontFamilyController.jsx

@@ -0,0 +1,11 @@
+import { useEffect } from "react";
+import { useSelectedFontFamily } from "@logics_configs";
+
+export const FontFamilyController = () => {
+    const { currentSelectedFontFamily } = useSelectedFontFamily();
+    useEffect(() => {
+        document.documentElement.style.setProperty("--font_family", currentSelectedFontFamily.data);
+    }, [currentSelectedFontFamily.data]);
+
+    return null;
+};