feat: add inline referral commission editing in admin user card

Admins can now edit individual referral commission percent directly
in the user detail card. Shows "Default" when no custom value is set.

src/api/adminUsers.ts

@@ -447,6 +447,17 @@ export const adminUsersApi = {
     return response.data;
   },
 
+  // Update referral commission
+  updateReferralCommission: async (
+    userId: number,
+    commissionPercent: number | null,
+  ): Promise<{ success: boolean; message: string }> => {
+    const response = await apiClient.post(`/cabinet/admin/users/${userId}/referral-commission`, {
+      commission_percent: commissionPercent,
+    });
+    return response.data;
+  },
+
   // Delete user (soft delete, does NOT remove from Remnawave)
   deleteUser: async (
     userId: number,