chore: finish frontend ESLint migration #18

Enable every plugin recommended preset and replace Biome with ESLint formatting.

Preserve API contracts and JSX whitespace; verify source, tests, builds and tooling.

vitest.config.ts

@@ -1,6 +1,6 @@
-import { fileURLToPath, URL } from "node:url";
 import react from "@vitejs/plugin-react";
 import { playwright } from "@vitest/browser-playwright";
+import { fileURLToPath, URL } from "node:url";
 import { configDefaults, defineConfig } from "vitest/config";
 
 const CI_TEST_TIMEOUT_MS = 15_000;
@@ -10,61 +10,61 @@ const LAYOUT_WIDE_WIDTH = 1280;
 
 export default defineConfig({
 	plugins: [react()],
-	resolve: { alias: { "@": fileURLToPath(new URL("./src", import.meta.url)) } },
+	resolve: { alias: { "@": fileURLToPath(new URL("src", import.meta.url)) } },
 	test: {
-		// CI runs the UI scenarios with coverage on a slower runner.
-		testTimeout: process.env.CI ? CI_TEST_TIMEOUT_MS : undefined,
+		coverage: {
+			exclude: ["src/test/**", "**/*.test.{ts,tsx}", "**/*.stories.tsx"],
+			include: ["src/**/*.{ts,tsx}", "packages/*/src/**/*.{ts,tsx}"],
+			reporter: ["text", "html", "lcov"],
+			thresholds: {
+				branches: 75,
+				functions: 75,
+				lines: 83,
+				statements: 82,
+			},
+		},
 		projects: [
 			{
 				extends: true,
 				test: {
-					name: "unit",
 					environment: "jsdom",
 					exclude: [...configDefaults.exclude, "**/*.browser.test.tsx"],
+					name: "unit",
 					setupFiles: "./src/test/setup.ts",
 				},
 			},
 			{
 				extends: true,
 				test: {
-					name: "browser",
-					include: ["src/**/*.browser.test.tsx"],
 					browser: {
 						enabled: true,
-						provider: playwright(),
 						headless: true,
 						instances: [
 							{
 								browser: "chromium",
 								name: "browser-narrow",
 								viewport: {
-									width: LAYOUT_NARROW_WIDTH,
 									height: LAYOUT_VIEWPORT_HEIGHT,
+									width: LAYOUT_NARROW_WIDTH,
 								},
 							},
 							{
 								browser: "chromium",
 								name: "browser-wide",
 								viewport: {
-									width: LAYOUT_WIDE_WIDTH,
 									height: LAYOUT_VIEWPORT_HEIGHT,
+									width: LAYOUT_WIDE_WIDTH,
 								},
 							},
 						],
+						provider: playwright(),
 					},
+					include: ["src/**/*.browser.test.tsx"],
+					name: "browser",
 				},
 			},
 		],
-		coverage: {
-			include: ["src/**/*.{ts,tsx}", "packages/*/src/**/*.{ts,tsx}"],
-			exclude: ["src/test/**", "**/*.test.{ts,tsx}", "**/*.stories.tsx"],
-			reporter: ["text", "html", "lcov"],
-			thresholds: {
-				statements: 82,
-				branches: 75,
-				functions: 75,
-				lines: 83,
-			},
-		},
+		// CI runs the UI scenarios with coverage on a slower runner.
+		testTimeout: process.env.CI ? CI_TEST_TIMEOUT_MS : undefined,
 	},
 });