test: exclude Playwright e2e tests from vitest

Add vitest configuration to exclude tests/e2e/** directory from vitest
runs. This prevents vitest from attempting to execute Playwright test
files, which was causing CI failures.

The e2e tests should only be run via the dedicated test:e2e npm script
which uses Playwright's test runner.

vitest.config.ts

@@ -0,0 +1,14 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    exclude: [
+      "**/node_modules/**",
+      "**/dist/**",
+      "**/cypress/**",
+      "**/.{idea,git,cache,output,temp}/**",
+      "**/{karma,rollup,webpack,vite,vitest,jest,ava,babel,nyc,cypress,tsup,build,eslint,prettier}.config.*",
+      "**/tests/e2e/**", // Exclude Playwright e2e tests
+    ],
+  },
+});