fix: audit fixes - magic strings to constants, frontend any/catch, LB tests

Backend:
- Define OrderTypeBalance/Subscription, EntityStatusActive, DeductionType*,
  NotificationStatus* constants in payment/types.go
- Replace all magic strings in payment_order, payment_fulfillment, payment_refund
- Add local constants in easypay.go (tradeStatusSuccess, signTypeMD5)
- Add 27 unit tests for load balancer (filterByLimits, pickLeastAmount,
  getInstanceChannelLimits, startOfDay)

Frontend:
- Remove all `any` types in SettingsView.vue (18 catch blocks + 1 payload)
- Fix bare catch blocks in PaymentResultView, PaymentView
- Add `unknown` type annotation to all catch blocks

chore: bump version to 0.1.108.140

frontend/src/views/user/PaymentView.vue

@@ -374,7 +374,7 @@ onMounted(async () => {
     if (checkout.value.balance_disabled) {
       activeTab.value = 'subscription'
     }
-  } catch (err: unknown) { console.error('Failed to load checkout info:', err) }
+  } catch (err: unknown) { appStore.showError(extractApiErrorMessage(err, t('common.error'))) }
   finally { loading.value = false }
 })
 </script>