feat(nav): add MobileTabBar with active state and safe-area padding

Fixed vitest resolve conditions to use browser entry for Svelte 5.

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

frontend/src/lib/nav/MobileTabBar.svelte

@@ -0,0 +1,22 @@
+<script lang="ts">
+	import { page } from '$app/stores';
+	import { mobileNavItems } from './nav';
+</script>
+
+<nav
+	aria-label="Hauptnavigation"
+	class="fixed bottom-0 w-full flex justify-around bg-white border-t pb-[env(safe-area-inset-bottom,20px)] md:hidden"
+>
+	{#each mobileNavItems as item (item.href)}
+		{@const active = $page.url.pathname.startsWith(item.href)}
+		<a
+			href={item.href}
+			aria-current={active ? 'page' : undefined}
+			class="flex flex-col items-center gap-1 py-2 px-3 rounded-[var(--radius-md)] text-[10px] font-[var(--font-sans)] min-h-[44px] min-w-[44px] {active
+				? 'bg-[var(--green-tint)] text-[var(--green-dark)] font-medium'
+				: ''}"
+		>
+			{item.label}
+		</a>
+	{/each}
+</nav>

frontend/src/lib/nav/MobileTabBar.test.ts

@@ -0,0 +1,47 @@
+import { describe, it, expect, vi } from 'vitest';
+import { render, screen } from '@testing-library/svelte';
+import MobileTabBar from './MobileTabBar.svelte';
+
+vi.mock('$app/stores', () => {
+	const { readable } = require('svelte/store');
+	return {
+		page: readable({ url: new URL('http://localhost/planner') })
+	};
+});
+
+describe('MobileTabBar', () => {
+	it('renders 4 nav items', () => {
+		render(MobileTabBar);
+		const links = screen.getAllByRole('link');
+		expect(links).toHaveLength(4);
+	});
+
+	it('renders correct labels', () => {
+		render(MobileTabBar);
+		expect(screen.getByText('Planer')).toBeInTheDocument();
+		expect(screen.getByText('Rezepte')).toBeInTheDocument();
+		expect(screen.getByText('Einkauf')).toBeInTheDocument();
+		expect(screen.getByText('Einstellungen')).toBeInTheDocument();
+	});
+
+	it('links have correct hrefs', () => {
+		render(MobileTabBar);
+		const links = screen.getAllByRole('link');
+		expect(links[0]).toHaveAttribute('href', '/planner');
+		expect(links[1]).toHaveAttribute('href', '/recipes');
+		expect(links[2]).toHaveAttribute('href', '/shopping');
+		expect(links[3]).toHaveAttribute('href', '/settings');
+	});
+
+	it('marks active item with aria-current="page"', () => {
+		render(MobileTabBar);
+		const plannerLink = screen.getByRole('link', { name: /planer/i });
+		expect(plannerLink).toHaveAttribute('aria-current', 'page');
+	});
+
+	it('non-active items do not have aria-current', () => {
+		render(MobileTabBar);
+		const recipesLink = screen.getByRole('link', { name: /rezepte/i });
+		expect(recipesLink).not.toHaveAttribute('aria-current');
+	});
+});

frontend/vite.config.ts

@@ -0,0 +1,16 @@
+import { sveltekit } from '@sveltejs/kit/vite';
+import { defineConfig } from 'vitest/config';
+import tailwindcss from '@tailwindcss/vite';
+
+export default defineConfig({
+	plugins: [tailwindcss(), sveltekit()],
+	test: {
+		include: ['src/**/*.{test,spec}.{js,ts}'],
+		globals: true,
+		environment: 'jsdom',
+		setupFiles: ['src/test-setup.ts']
+	},
+	resolve: {
+		conditions: ['browser']
+	}
+});