upgrade auf svelte5

vitest-setup-client.ts

@@ -0,0 +1,18 @@
+import '@testing-library/jest-dom/vitest';
+import { vi } from 'vitest';
+
+// required for svelte5 + jsdom as jsdom does not support matchMedia
+Object.defineProperty(window, 'matchMedia', {
+	writable: true,
+	enumerable: true,
+	value: vi.fn().mockImplementation((query) => ({
+		matches: false,
+		media: query,
+		onchange: null,
+		addEventListener: vi.fn(),
+		removeEventListener: vi.fn(),
+		dispatchEvent: vi.fn()
+	}))
+});
+
+// add more mocks here if you need them