feat: rating stars on recipe cards (Search, Explore)

New lib/recipe-ratings.ts helper batches avg score + review count for
a set of recipe ids in one grouped query, kept separate from the main
paginated/sorted search query rather than joining+grouping it directly
(would've forced grouping by every selected column). Wired into
/api/v1/search and the Explore page's trending/recent queries;
SearchResultCard renders the star only when a recipe has at least one
rating.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@epicure/web",
-  "version": "0.20.0",
+  "version": "0.21.0",
   "private": true,
   "scripts": {
     "dev": "next dev",