test(ocr): fix track_reactivity_loss in OcrTrainingCard spec

Two root causes:

1. In-flight test: resolveFetch() was the last line, leaving the async
   finally-block writing `training = false` after cleanup destroyed the
   component. Awaiting the button becoming re-enabled ensures the finally
   block settles before cleanup runs.

2. Success-dismiss test: startTraining() schedules setTimeout(5000) which
   fired after cleanup destroyed the component. vi.useFakeTimers() +
   vi.runAllTimers() scoped to the describe block drains the timer while
   the component is still alive.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/ocr/OcrTrainingCard.svelte.spec.ts

@@ -1,4 +1,4 @@
-import { afterEach, describe, expect, it, vi } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { cleanup, render } from 'vitest-browser-svelte';
 import { page } from 'vitest/browser';
 import OcrTrainingCard from './OcrTrainingCard.svelte';
@@ -74,6 +74,12 @@ describe('OcrTrainingCard — enabled state', () => {
 });
 
 describe('OcrTrainingCard — success dismiss button', () => {
+	beforeEach(() => vi.useFakeTimers());
+	afterEach(() => {
+		vi.runAllTimers();
+		vi.useRealTimers();
+	});
+
 	it('dismiss button has 44×44px touch target (h-11 w-11)', async () => {
 		vi.stubGlobal('fetch', vi.fn().mockResolvedValue({ ok: true }));
 
@@ -108,7 +114,9 @@ describe('OcrTrainingCard — in-flight state', () => {
 		// While fetch is still pending the button label becomes "…"
 		await expect.element(page.getByRole('button', { name: '…' })).toBeInTheDocument();
 
-		// Cleanup: resolve the pending promise
 		resolveFetch({ ok: false });
+		await expect
+			.element(page.getByRole('button', { name: /Training starten/i }))
+			.not.toBeDisabled();
 	});
 });