fix: avoid overridden Vite config warning with Vitest 4 (#15121)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: teemingc <54401897+teemingc@users.noreply.github.com>
Co-authored-by: Ben McCann <322311+benmccann@users.noreply.github.com>

Author: 3 people

.changeset/eager-islands-cheer.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: avoid false-positive Vite config overridden warning when using Vitest 4

packages/kit/src/exports/vite/index.js

@@ -42,7 +42,7 @@ import { import_peer } from '../../utils/import.js';
 import { compact } from '../../utils/array.js';
 import { should_ignore } from './static_analysis/utils.js';
 
-const cwd = process.cwd();
+const cwd = posixify(process.cwd());
 
 /** @type {import('./types.js').EnforcedConfig} */
 const enforced_config = {