fix(i18n): translate remaining recipe card/detail strings, localize AI responses

Recipe cards, the recipe detail page, and meal planner still rendered raw
"{n} servings"/"{n}m cook"/"{n} srv" text and untranslated difficulty labels
outside the earlier i18n pass. Also wires the user's locale into AI features
that previously always answered in English regardless of app language:
recipe chat, ingredient substitution, recipe ideas, and generate-from-idea.
The recipe-language picker in the AI generate dialog now defaults to the
user's locale instead of always defaulting to English.

apps/web/components/recipe/recipe-card.tsx

@@ -1,4 +1,5 @@
 import Link from "next/link";
+import { useTranslations } from "next-intl";
 import { Clock, Users, Lock, Globe, Link2 } from "lucide-react";
 import { Badge } from "@/components/ui/badge";
 import { Card, CardContent, CardFooter, CardHeader } from "@/components/ui/card";
@@ -30,6 +31,7 @@ const DIFFICULTY_COLOR = {
 } as const;
 
 export function RecipeCard({ recipe }: { recipe: Recipe }) {
+  const t = useTranslations("recipe");
   const cover = recipe.photos?.find((p) => p.isCover) ?? recipe.photos?.[0];
   const totalMins = (recipe.prepMins ?? 0) + (recipe.cookMins ?? 0);
   const VisibilityIcon = VISIBILITY_ICON[recipe.visibility];
@@ -68,12 +70,12 @@ export function RecipeCard({ recipe }: { recipe: Recipe }) {
             {totalMins > 0 && (
               <span className="flex items-center gap-1">
                 <Clock className="h-3 w-3" />
-                {totalMins}m
+                {t("total", { mins: totalMins })}
               </span>
             )}
             {recipe.difficulty && (
               <Badge variant={DIFFICULTY_COLOR[recipe.difficulty]} className="text-xs h-4">
-                {recipe.difficulty}
+                {t(`difficulty.${recipe.difficulty}`)}
               </Badge>
             )}
           </div>