fix: align TypeScript types with backend referral schemas

- Add campaign_name field to ReferralEarning interface
- Fix telegram_id to number | null in TopReferrerItem (email-only users)
- Add email field to TopReferrerItem

src/api/admin.ts

@@ -243,8 +243,9 @@ export interface DashboardStats {
 
 export interface TopReferrerItem {
   user_id: number;
-  telegram_id: number;
+  telegram_id: number | null;
   username?: string;
+  email?: string | null;
   display_name: string;
   invited_count: number;
   invited_today: number;

src/api/referral.ts

@@ -17,6 +17,7 @@ interface ReferralEarning {
   reason: string;
   referral_username: string | null;
   referral_first_name: string | null;
+  campaign_name: string | null;
   created_at: string;
 }