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.svelte

@@ -0,0 +1,62 @@
+<script lang="ts">
+	interface IngredientOverlap {
+		ingredientName?: string;
+		days?: string[];
+	}
+
+	let {
+		score,
+		ingredientOverlaps = [],
+		showReviewLink = false
+	}: {
+		score: number;
+		ingredientOverlaps?: IngredientOverlap[];
+		showReviewLink?: boolean;
+	} = $props();
+
+	let percentage = $derived(Math.round((score / 10) * 100));
+</script>
+
+<div class="rounded-[var(--radius-lg)] border border-[var(--yellow-light)] bg-[var(--yellow-tint)] p-4">
+	<div class="flex items-baseline gap-1">
+		<span class="font-[var(--font-display)] text-[28px] font-[300] text-[var(--color-text)] md:text-[40px]">
+			{score}
+		</span>
+		<span class="font-[var(--font-sans)] text-[13px] text-[var(--color-text-muted)]">/10</span>
+		<span class="ml-1 font-[var(--font-sans)] text-[12px] text-[var(--color-text-muted)]">Abwechslungs-Score</span>
+	</div>
+
+	<!-- Progress bar -->
+	<div
+		class="mt-2 h-[4px] w-full overflow-hidden rounded-full bg-[var(--yellow-light)]"
+	>
+		<div
+			role="progressbar"
+			aria-valuenow={score}
+			aria-valuemin={0}
+			aria-valuemax={10}
+			class="h-full rounded-full bg-[var(--yellow)] transition-all"
+			style="width: {percentage}%"
+		></div>
+	</div>
+
+	<!-- Ingredient overlap warnings -->
+	{#if ingredientOverlaps.length > 0}
+		<ul class="mt-3 space-y-1">
+			{#each ingredientOverlaps as overlap}
+				<li class="font-[var(--font-sans)] text-[12px] text-[var(--yellow-text)]">
+					⚠ <span>{overlap.ingredientName}</span> in <span>{overlap.days?.length ?? 0} Mahlzeiten</span>
+				</li>
+			{/each}
+		</ul>
+	{/if}
+
+	{#if showReviewLink}
+		<a
+			href="/planner/variety"
+			class="mt-3 block font-[var(--font-sans)] text-[12px] font-medium text-[var(--yellow-text)] hover:underline"
+		>
+			Variety überprüfen →
+		</a>
+	{/if}
+</div>