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/variations-dialog.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import { useState } from "react";
+import { useTranslations } from "next-intl";
 import { useRouter } from "next/navigation";
 import { FakeProgressBar } from "@/components/ui/fake-progress-bar";
 import { Sparkles, Loader2, ChevronRight, Replace } from "lucide-react";
@@ -61,6 +62,7 @@ export function VariationsDialog({
   open: boolean;
   onOpenChange: (open: boolean) => void;
 }) {
+  const t = useTranslations("recipe");
   const router = useRouter();
   const [generating, setGenerating] = useState(false);
   const [applying, setApplying] = useState<number | null>(null);
@@ -170,7 +172,7 @@ export function VariationsDialog({
               <Label htmlFor="directions">Directions <span className="text-muted-foreground font-normal">(optional)</span></Label>
               <Textarea
                 id="directions"
-                placeholder="e.g. make it vegan, use only pantry staples, reduce sugar…"
+                placeholder={t("variationsDirectionsPlaceholder")}
                 value={directions}
                 onChange={(e) => setDirections(e.target.value)}
                 disabled={generating}