more TS fixes + tests

src/types.ts

@@ -772,4 +772,16 @@ export interface UserAchievement {
   user_id: string; // UUID
   achievement_id: number;
   achieved_at: string; // TIMESTAMPTZ
+}
+
+/**
+ * Represents a user's entry on the leaderboard.
+ * Returned by the `getLeaderboard` database function.
+ */
+export interface LeaderboardUser {
+  user_id: string;
+  full_name: string | null;
+  avatar_url: string | null;
+  points: number;
+  rank: string; // RANK() returns a bigint, which the pg driver returns as a string.
 }