feat(auth): add BrandPanel component for signup screen

Renders brand identity with logo, app name, tagline, and feature icons
on green-dark background. Responsive: banner on mobile, 440px column
on desktop.

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

frontend/src/lib/auth/BrandPanel.svelte

@@ -0,0 +1,32 @@
+<script lang="ts">
+</script>
+
+<div
+	class="bg-[var(--green-dark)] flex flex-col items-center justify-center
+		px-6 py-7 text-center
+		md:w-[440px] md:min-h-screen md:px-10 md:py-12"
+>
+	<span class="text-[28px] md:text-[64px]" aria-hidden="true">🥗</span>
+
+	<h1
+		class="mt-2 font-[var(--font-display)] text-[22px] font-medium tracking-[-0.02em] text-white
+			md:mt-3 md:text-[36px]"
+	>
+		Mealprep
+	</h1>
+
+	<p class="mt-1 text-[12px] text-[var(--green-light)] md:mt-2 md:text-[15px]">
+		Plan meals, eat well, waste less
+	</p>
+
+	<div class="mt-8 hidden gap-3 md:flex">
+		{#each [{ emoji: '📅', label: 'Plan' }, { emoji: '🍳', label: 'Cook' }, { emoji: '🛒', label: 'Shop' }] as feature (feature.label)}
+			<div
+				class="flex flex-col items-center gap-1 rounded-lg bg-white/10 px-4 py-3"
+			>
+				<span class="text-[18px]">{feature.emoji}</span>
+				<span class="text-[10px] text-[var(--green-light)]">{feature.label}</span>
+			</div>
+		{/each}
+	</div>
+</div>

frontend/src/lib/auth/BrandPanel.test.ts

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+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/svelte';
+import BrandPanel from './BrandPanel.svelte';
+
+describe('BrandPanel', () => {
+	it('renders the app name', () => {
+		render(BrandPanel);
+		expect(screen.getByText('Mealprep')).toBeInTheDocument();
+	});
+
+	it('renders the tagline', () => {
+		render(BrandPanel);
+		expect(screen.getByText('Plan meals, eat well, waste less')).toBeInTheDocument();
+	});
+
+	it('renders the logo emoji', () => {
+		render(BrandPanel);
+		expect(screen.getByText('🥗')).toBeInTheDocument();
+	});
+
+	it('renders three feature icons with labels', () => {
+		render(BrandPanel);
+		expect(screen.getByText('Plan')).toBeInTheDocument();
+		expect(screen.getByText('Cook')).toBeInTheDocument();
+		expect(screen.getByText('Shop')).toBeInTheDocument();
+	});
+
+	it('renders feature emojis', () => {
+		render(BrandPanel);
+		expect(screen.getByText('📅')).toBeInTheDocument();
+		expect(screen.getByText('🍳')).toBeInTheDocument();
+		expect(screen.getByText('🛒')).toBeInTheDocument();
+	});
+});