feat(planner): implement C1 weekly planner home screen (#26)

Three-breakpoint layout (mobile/tablet/desktop) with VarietyScoreCard,
WeekStrip, DayMealCard components. Server loads week plan and variety
score via API; read-only role behavior derived from benutzer.rolle.

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

frontend/src/lib/planner/VarietyScoreCard.test.ts

@@ -0,0 +1,56 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/svelte';
+import VarietyScoreCard from './VarietyScoreCard.svelte';
+
+const baseProps = {
+	score: 7.5,
+	ingredientOverlaps: [],
+	showReviewLink: false
+};
+
+describe('VarietyScoreCard', () => {
+	it('renders the variety score', () => {
+		render(VarietyScoreCard, { props: baseProps });
+		expect(screen.getByText('7.5')).toBeTruthy();
+	});
+
+	it('renders "/10" denominator', () => {
+		render(VarietyScoreCard, { props: baseProps });
+		expect(screen.getByText('/10')).toBeTruthy();
+	});
+
+	it('renders a progress bar with correct aria attributes', () => {
+		render(VarietyScoreCard, { props: baseProps });
+		const bar = screen.getByRole('progressbar');
+		expect(bar.getAttribute('aria-valuenow')).toBe('7.5');
+		expect(bar.getAttribute('aria-valuemin')).toBe('0');
+		expect(bar.getAttribute('aria-valuemax')).toBe('10');
+	});
+
+	it('renders ingredient overlap warnings', () => {
+		render(VarietyScoreCard, {
+			props: {
+				...baseProps,
+				ingredientOverlaps: [{ ingredientName: 'Tomate', days: ['2026-03-30', '2026-03-31'] }]
+			}
+		});
+		expect(screen.getByText(/Tomate/)).toBeTruthy();
+		expect(screen.getByText(/2 Mahlzeiten/)).toBeTruthy();
+	});
+
+	it('shows review link when showReviewLink is true', () => {
+		render(VarietyScoreCard, { props: { ...baseProps, showReviewLink: true } });
+		const link = screen.getByRole('link', { name: /Variety.*überprüfen|Review variety/i });
+		expect(link).toBeTruthy();
+	});
+
+	it('hides review link by default', () => {
+		render(VarietyScoreCard, { props: baseProps });
+		expect(screen.queryByRole('link', { name: /variety/i })).toBeNull();
+	});
+
+	it('renders with score 0', () => {
+		render(VarietyScoreCard, { props: { ...baseProps, score: 0 } });
+		expect(screen.getByText('0')).toBeTruthy();
+	});
+});