fix: address ESLint warnings and add Vitest configuration

- Add ESLint flat config with Svelte and TypeScript support
- Fix unused variables and component prop naming
- Add Vitest browser testing setup with Playwright
- Configure separate test projects for client and server code

web/vite.config.ts

@@ -1,13 +1,16 @@
+import devtoolsJson from 'vite-plugin-devtools-json';
+import { defineConfig } from 'vitest/config';
+import { playwright } from '@vitest/browser-playwright';
 import { sveltekit } from '@sveltejs/kit/vite';
 import tailwindcss from '@tailwindcss/vite';
-import { defineConfig, type Plugin } from 'vite';
+import { type Plugin } from 'vite';
 import { execSync } from 'child_process';
 import { fontSubsetPlugin, type FontSubsetConfig } from './vite-plugin-font-subset';
 
 // Character sets for font subsetting
 const TITLE_CHARS = 'PACMN-';
-const COMMON_CHARS =
-	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 .,!?':;-_()\/@#&*+=%<>";
+
+const COMMON_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 .,!?':;-_()/@#&*+=%<>";
 
 const fontConfig: FontSubsetConfig = {
 	fonts: [
@@ -15,11 +18,13 @@ const fontConfig: FontSubsetConfig = {
 			source: '@fontsource/russo-one/files/russo-one-latin-400-normal.woff2',
 			whitelist: TITLE_CHARS
 		},
+
 		{
 			source: '@fontsource/outfit/files/outfit-latin-400-normal.woff2',
 			whitelist: COMMON_CHARS,
 			family: 'Outfit'
 		},
+
 		{
 			source: '@fontsource/outfit/files/outfit-latin-500-normal.woff2',
 			whitelist: COMMON_CHARS,
@@ -39,10 +44,7 @@ function pacmanVersionPlugin(): Plugin {
 		}
 
 		try {
-			const hash = execSync('git rev-parse --short HEAD', {
-				encoding: 'utf8',
-				stdio: ['pipe', 'pipe', 'pipe']
-			}).trim();
+			const hash = execSync('git rev-parse --short HEAD', { encoding: 'utf8', stdio: ['pipe', 'pipe', 'pipe'] }).trim();
 
 			if (hash) {
 				return hash;
@@ -56,8 +58,10 @@ function pacmanVersionPlugin(): Plugin {
 
 	return {
 		name: 'pacman-version',
+
 		config(_, { mode }) {
 			const version = getVersion(mode);
+
 			console.log(`[pacman-version] Using version: ${version}`);
 
 			return {
@@ -70,10 +74,16 @@ function pacmanVersionPlugin(): Plugin {
 }
 
 export default defineConfig({
-	plugins: [fontSubsetPlugin(fontConfig), pacmanVersionPlugin(), sveltekit(), tailwindcss()],
-	build: {
-		target: 'es2022'
-	},
+	plugins: [
+		fontSubsetPlugin(fontConfig),
+		pacmanVersionPlugin(),
+		sveltekit(),
+		tailwindcss(),
+		devtoolsJson()
+	],
+
+	build: { target: 'es2022' },
+
 	server: {
 		proxy: {
 			'/api': {
@@ -81,5 +91,39 @@ export default defineConfig({
 				changeOrigin: true
 			}
 		}
+	},
+
+	test: {
+		expect: { requireAssertions: true },
+
+		projects: [
+			{
+				extends: './vite.config.ts',
+
+				test: {
+					name: 'client',
+
+					browser: {
+						enabled: true,
+						provider: playwright(),
+						instances: [{ browser: 'chromium', headless: true }]
+					},
+
+					include: ['src/**/*.svelte.{test,spec}.{js,ts}'],
+					exclude: ['src/lib/server/**']
+				}
+			},
+
+			{
+				extends: './vite.config.ts',
+
+				test: {
+					name: 'server',
+					environment: 'node',
+					include: ['src/**/*.{test,spec}.{js,ts}'],
+					exclude: ['src/**/*.svelte.{test,spec}.{js,ts}']
+				}
+			}
+		]
 	}
 });