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/lib/changelog.ts

@@ -1,5 +1,5 @@
 // Mirrors CHANGELOG.md at the repo root — update both together.
-export const APP_VERSION = "0.20.0";
+export const APP_VERSION = "0.21.0";
 
 export type ChangelogEntry = {
   version: string;
@@ -11,6 +11,13 @@ export type ChangelogEntry = {
 };
 
 export const CHANGELOG: ChangelogEntry[] = [
+  {
+    version: "0.21.0",
+    date: "2026-07-13 22:34",
+    added: [
+      "**Rating stars on recipe cards** — average rating and review count now show on Search and Explore results, not just the recipe detail page.",
+    ],
+  },
   {
     version: "0.20.0",
     date: "2026-07-13 22:26",