feat: add trending/leaderboard for collections

New collection_favorites table lets users star public collections.
/collections/explore mirrors the recipe explore page: trending (star
count in last 7 days) and recently-added public collections. Linked
from the "Discover" button on the collections page.

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

packages/db/src/migrations/0022_foamy_loki.sql

@@ -0,0 +1,10 @@
+CREATE TABLE "collection_favorites" (
+	"user_id" text NOT NULL,
+	"collection_id" text NOT NULL,
+	"created_at" timestamp DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+ALTER TABLE "collection_favorites" ADD CONSTRAINT "collection_favorites_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "collection_favorites" ADD CONSTRAINT "collection_favorites_collection_id_collections_id_fk" FOREIGN KEY ("collection_id") REFERENCES "public"."collections"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+CREATE INDEX "collection_favorites_collection_idx" ON "collection_favorites" USING btree ("collection_id");--> statement-breakpoint
+CREATE UNIQUE INDEX "collection_favorites_user_collection_idx" ON "collection_favorites" USING btree ("user_id","collection_id");

packages/db/src/migrations/meta/_journal.json

@@ -155,6 +155,13 @@
       "when": 1783602591480,
       "tag": "0021_mysterious_madame_masque",
       "breakpoints": true
+    },
+    {
+      "idx": 22,
+      "version": "7",
+      "when": 1783603737477,
+      "tag": "0022_foamy_loki",
+      "breakpoints": true
     }
   ]
 }