feat(admin): add OCR training card to admin/system page

- TrainingHistory.svelte: responsive table with status badges
  (green/red/animated pulse), keyed iteration, empty-state row
- OcrTrainingCard.svelte: shows available blocks/docs, disabled states
  (< 5 blocks, service down), in-flight "…" state, 5s success message,
  embeds TrainingHistory
- Wired into admin/system/+page.svelte via fetchTrainingInfo() in $effect
- Regenerated api.ts with OcrTrainingRun + TrainingInfoResponse types
- TRAINING_ALREADY_RUNNING error code in errors.ts + de/en/es translations
- 7 OcrTrainingCard Vitest tests

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

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

@@ -0,0 +1,96 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import OcrTrainingCard from './OcrTrainingCard.svelte';
+
+afterEach(cleanup);
+afterEach(() => vi.restoreAllMocks());
+
+const baseInfo = {
+	availableBlocks: 10,
+	totalOcrBlocks: 20,
+	availableDocuments: 3,
+	ocrServiceAvailable: true,
+	lastRun: null,
+	runs: []
+};
+
+describe('OcrTrainingCard — disabled states', () => {
+	it('disables button and shows hint when availableBlocks is 0', async () => {
+		render(OcrTrainingCard, { trainingInfo: { ...baseInfo, availableBlocks: 0 } });
+
+		const btn = page.getByRole('button', { name: /Training starten/i });
+		await expect.element(btn).toBeDisabled();
+		await expect
+			.element(page.getByText(/Mindestens 5 geprüfte Blöcke erforderlich/i))
+			.toBeInTheDocument();
+	});
+
+	it('disables button and shows hint when availableBlocks is less than 5', async () => {
+		render(OcrTrainingCard, { trainingInfo: { ...baseInfo, availableBlocks: 3 } });
+
+		const btn = page.getByRole('button', { name: /Training starten/i });
+		await expect.element(btn).toBeDisabled();
+		await expect.element(page.getByText(/Mindestens 5/i)).toBeInTheDocument();
+	});
+
+	it('disables button and shows service-down warning when ocrServiceAvailable is false', async () => {
+		render(OcrTrainingCard, { trainingInfo: { ...baseInfo, ocrServiceAvailable: false } });
+
+		const btn = page.getByRole('button', { name: /Training starten/i });
+		await expect.element(btn).toBeDisabled();
+		await expect.element(page.getByText(/OCR-Dienst ist nicht erreichbar/i)).toBeInTheDocument();
+	});
+
+	it('does not show service-down warning when blocks are insufficient', async () => {
+		// tooFewBlocks hint takes priority over serviceDown hint
+		render(OcrTrainingCard, {
+			trainingInfo: { ...baseInfo, availableBlocks: 2, ocrServiceAvailable: false }
+		});
+
+		await expect.element(page.getByText(/Mindestens 5/i)).toBeInTheDocument();
+		// serviceDown text should NOT appear because tooFewBlocks branch hides it
+		const serviceMsg = document.querySelector('.text-orange-600');
+		expect(serviceMsg).toBeNull();
+	});
+});
+
+describe('OcrTrainingCard — enabled state', () => {
+	it('enables button when availableBlocks >= 5 and service is up', async () => {
+		render(OcrTrainingCard, { trainingInfo: baseInfo });
+
+		const btn = page.getByRole('button', { name: /Training starten/i });
+		await expect.element(btn).not.toBeDisabled();
+	});
+
+	it('shows block count info text', async () => {
+		render(OcrTrainingCard, {
+			trainingInfo: { ...baseInfo, availableBlocks: 7, totalOcrBlocks: 15 }
+		});
+
+		await expect.element(page.getByText(/7/)).toBeInTheDocument();
+		await expect.element(page.getByText(/von 15 OCR-Blöcken/i)).toBeInTheDocument();
+	});
+});
+
+describe('OcrTrainingCard — in-flight state', () => {
+	it('shows "…" while POST is in-flight', async () => {
+		let resolveFetch!: (v: unknown) => void;
+		const pendingFetch = new Promise((resolve) => {
+			resolveFetch = resolve;
+		});
+
+		vi.stubGlobal('fetch', vi.fn().mockReturnValue(pendingFetch));
+
+		render(OcrTrainingCard, { trainingInfo: baseInfo });
+
+		const btn = page.getByRole('button', { name: /Training starten/i });
+		await btn.click();
+
+		// 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 });
+	});
+});