feat: copy/export as Markdown wherever print exists

Added a shared ExportMarkdownButton (copy to clipboard / download .md)
next to every existing print button: recipe, shopping list,
collection, meal plan, pantry. Each surface gets a small serializer in
lib/markdown/ built from data already in scope at that page — no new
queries except pantry, where items now thread through as a prop to
PantryPageHeader instead of being fetched only for PantryManager.

Also fixes an unrelated bug hit while verifying the collection export:
RecipeCard called the client-only useTranslations() hook without
"use client", so it rendered fine everywhere it happened to run inside
an already-client tree but 500'd — "Couldn't find next-intl config
file" — when Next tried to run it as a Server Component, which only
happens on the collection detail page (its only caller). Collections
with recipes in them were completely broken.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/app/(app)/meal-plan/page.tsx

@@ -9,6 +9,8 @@ import { MealPlanner } from "@/components/meal-plan/meal-planner";
 import { ShareMealPlanButton } from "@/components/meal-plan/share-meal-plan-button";
 import { WeeklyNutritionBar } from "@/components/nutrition/weekly-nutrition-bar";
 import { cn } from "@/lib/utils";
+import { ExportMarkdownButton } from "@/components/shared/export-markdown-button";
+import { mealPlanToMarkdown } from "@/lib/markdown/meal-plan";
 import { getMessages, formatMessage } from "@/lib/i18n/server";
 
 export const metadata: Metadata = { title: "Meal Plan" };
@@ -98,6 +100,10 @@ export default async function MealPlanPage({
             <Printer className="h-4 w-4" />
             {msgs.common.print}
           </Link>
+          <ExportMarkdownButton
+            markdown={mealPlanToMarkdown({ label, entries })}
+            filename={`meal-plan-${weekStart}`}
+          />
           <Link href={`/meal-plan?week=${prevWeek}`} className={cn(buttonVariants({ variant: "outline", size: "sm" }))}>
             <ChevronLeft className="h-4 w-4" />
           </Link>