chore: codify React component style

src/app/ui/App.tsx

@@ -1,5 +1,6 @@
 import { MantineProvider } from "@mantine/core";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import type { FC } from "react";
 import { BrowserRouter } from "react-router";
 import { AppRoutes, RouteErrorBoundary } from "@/app/routes";
 import { theme } from "@/app/theme";
@@ -9,7 +10,7 @@ const queryClient = new QueryClient({
 	defaultOptions: { queries: { refetchOnWindowFocus: false } },
 });
 
-export function App() {
+const App: FC = () => {
 	return (
 		<MantineProvider theme={theme} forceColorScheme="light">
 			<QueryClientProvider client={queryClient}>
@@ -23,4 +24,6 @@ export function App() {
 			</QueryClientProvider>
 		</MantineProvider>
 	);
-}
+};
+
+export { App };