feat(i18n): translate hardcoded strings across print, public recipe, and recipe management UI

Wires dozens of components and server pages to next-intl instead of hardcoded
English text, and adds a lightweight getMessages/formatMessage helper for
server components (print pages, public recipe page, cook metadata) since
next-intl/server isn't wired into this app's routing. Backfills missing
en/fr message keys that existing code already referenced but fr.json lacked.

apps/web/components/recipe/generate-content-button.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import { useState } from "react";
+import { useTranslations } from "next-intl";
 import { useRouter } from "next/navigation";
 import { Sparkles, Loader2 } from "lucide-react";
 import { toast } from "sonner";
@@ -21,6 +22,7 @@ export function GenerateContentButton({
   title: string;
   description?: string | null;
 }) {
+  const t = useTranslations("ai.generate");
   const router = useRouter();
   const [busy, setBusy] = useState(false);
 
@@ -38,8 +40,7 @@ export function GenerateContentButton({
       });
 
       if (!genRes.ok) {
-        const err = await genRes.json() as { error?: string };
-        toast.error(err.error ?? "Generation failed");
+        toast.error(t("contentGenerateFailed"));
         return;
       }
 
@@ -65,11 +66,11 @@ export function GenerateContentButton({
       });
 
       if (!saveRes.ok) {
-        toast.error("Failed to save generated content");
+        toast.error(t("contentSaveFailed"));
         return;
       }
 
-      toast.success("Ingredients and steps generated!");
+      toast.success(t("contentGenerated"));
       router.refresh();
     } finally {
       setBusy(false);