fix(admin): resolve incorrect crypto balance calculation fallback displaying fiat amount

app/api/merchants/route.ts

@@ -57,9 +57,9 @@ export async function GET() {
                 merchant_id, 
                 COALESCE(paid_network, 'SİSTEM') as network, 
                 COALESCE(paid_token, 'TRY') as token, 
-                SUM(COALESCE(paid_amount_crypto, amount)) as amount
+                SUM(CAST(COALESCE(paid_amount_crypto, '0') AS numeric)) as amount
             FROM transactions 
-            WHERE status = 'succeeded'
+            WHERE status = 'succeeded' AND paid_network IS NOT NULL
             GROUP BY merchant_id, paid_network, paid_token
         `);