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/substitute-ingredient-popover.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import { useState } from "react";
+import { useTranslations } from "next-intl";
 import { Shuffle, Loader2 } from "lucide-react";
 import {
   Popover,
@@ -29,6 +30,7 @@ export function SubstituteIngredientPopover({
   ingredient: string;
   recipeTitle: string;
 }) {
+  const t = useTranslations("substitute");
   const [open, setOpen] = useState(false);
   const [loading, setLoading] = useState(false);
   const [substitutions, setSubstitutions] = useState<Substitution[]>([]);
@@ -47,14 +49,14 @@ export function SubstituteIngredientPopover({
       });
       if (!res.ok) {
         const body = await res.json().catch(() => null) as { error?: string } | null;
-        setError(body?.error ?? "Couldn't fetch substitutes.");
+        setError(body?.error ?? t("fetchError"));
         return;
       }
       const data = await res.json() as { substitutions: Substitution[] };
       setSubstitutions(data.substitutions);
       setFetched(true);
     } catch {
-      setError("Couldn't fetch substitutes.");
+      setError(t("fetchError"));
     } finally {
       setLoading(false);
     }
@@ -69,18 +71,18 @@ export function SubstituteIngredientPopover({
     <Popover open={open} onOpenChange={handleOpen}>
       <PopoverTrigger
         className="h-5 w-5 opacity-0 group-hover:opacity-60 hover:opacity-100 transition-opacity shrink-0 inline-flex items-center justify-center rounded hover:bg-accent"
-        title={`Substitute for ${ingredient}`}
+        title={t("titleFor", { ingredient })}
       >
         <Shuffle className="h-3 w-3" />
       </PopoverTrigger>
       <PopoverContent className="w-80 p-3 space-y-3" align="start">
         <p className="text-xs font-semibold text-muted-foreground uppercase tracking-wide">
-          Substitutes for <span className="text-foreground normal-case">{ingredient}</span>
+          {t("substitutesFor")} <span className="text-foreground normal-case">{ingredient}</span>
         </p>
         {loading && (
           <div className="flex items-center gap-2 py-2 text-sm text-muted-foreground">
             <Loader2 className="h-3.5 w-3.5 animate-spin" />
-            Finding substitutes…
+            {t("finding")}
           </div>
         )}
         {!loading && substitutions.length > 0 && (
@@ -103,7 +105,7 @@ export function SubstituteIngredientPopover({
           <p className="text-sm text-destructive py-1">{error}</p>
         )}
         {!loading && fetched && substitutions.length === 0 && (
-          <p className="text-sm text-muted-foreground py-1">No substitutions found.</p>
+          <p className="text-sm text-muted-foreground py-1">{t("noneFound")}</p>
         )}
       </PopoverContent>
     </Popover>