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/recipes-grid.tsx

@@ -45,6 +45,7 @@ function SelectableRecipeCard({
   selectMode: boolean;
   onToggle: (id: string) => void;
 }) {
+  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];
@@ -139,12 +140,12 @@ function SelectableRecipeCard({
           {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 px-1.5">
-              {recipe.difficulty}
+              {t(`difficulty.${recipe.difficulty}`)}
             </Badge>
           )}
         </div>