add negative handler on amount field

src/pages/transaction/topup/TransactionTopup.tsx

@@ -158,8 +158,14 @@ const TransactionTopup = () => {
                     <Input
                       id="topupAmount"
                       type="number"
+                      min={0}
                       value={form.topupAmount}
-                      onChange={(e) => setForm({ ...form, topupAmount: e.target.value })}
+                      onChange={(e) => {
+                        const value = Number(e.target.value);
+                        if (value >= 0) {
+                          setForm({ ...form, topupAmount: String(value) });
+                        }
+                      }}
                     />
                   </div>
                   <div>