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)/pantry/page.tsx

@@ -16,16 +16,18 @@ export default async function PantryPage() {
     orderBy: asc(pantryItems.rawName),
   });
 
+  const mappedItems = items.map((i) => ({
+    id: i.id,
+    rawName: i.rawName,
+    quantity: i.quantity,
+    unit: i.unit,
+    expiresAt: i.expiresAt?.toISOString() ?? null,
+  }));
+
   return (
     <div className="space-y-6">
-      <PantryPageHeader />
-      <PantryManager initialItems={items.map((i) => ({
-        id: i.id,
-        rawName: i.rawName,
-        quantity: i.quantity,
-        unit: i.unit,
-        expiresAt: i.expiresAt?.toISOString() ?? null,
-      }))} />
+      <PantryPageHeader items={mappedItems} />
+      <PantryManager initialItems={mappedItems} />
     </div>
   );
 }