chore: codify React component style

src/app/routes/RouteErrorBoundary.test.tsx

@@ -1,5 +1,6 @@
 import { MantineProvider } from "@mantine/core";
 import { cleanup, render, screen, waitFor } from "@testing-library/react";
+import type { FC } from "react";
 import { MemoryRouter, useLocation, useNavigate } from "react-router";
 import { afterEach, describe, expect, it, vi } from "vitest";
 import { RouteErrorBoundary } from "./RouteErrorBoundary";
@@ -9,10 +10,11 @@ vi.mock("@/features/auth", () => ({
 	useAuth: () => ({ user: authenticated ? {} : null }),
 }));
 
-function ThrowingRoute(): never {
+const ThrowingRoute: FC = () => {
 	throw new Error("test route failure");
-}
-function HealthyRoute() {
+};
+
+const HealthyRoute: FC = () => {
 	return (
 		<div>
 			{useLocation().pathname === "/healthy" ? (
@@ -22,9 +24,11 @@ function HealthyRoute() {
 			)}
 		</div>
 	);
-}
-function RouteHarness() {
+};
+
+const RouteHarness: FC = () => {
 	const navigate = useNavigate();
+
 	return (
 		<>
 			<button type="button" onClick={() => navigate("/healthy")}>
@@ -35,7 +39,8 @@ function RouteHarness() {
 			</RouteErrorBoundary>
 		</>
 	);
-}
+};
+
 function renderBoundary(path: string) {
 	return render(
 		<MantineProvider>