implement collections page

packages/core/src/collection.ts

@@ -0,0 +1,10 @@
+import type { Bookmark } from "./bookmark.js"
+
+interface Collection {
+	id: string
+	name: string
+	description: string
+	bookmarks: Bookmark[]
+}
+
+export type { Collection }

packages/core/src/index.ts

@@ -1,3 +1,4 @@
 export * from "./bookmark.ts"
 export * from "./tag.ts"
 export * from "./user.ts"
+export * from "./collection.ts"