GitLab

- Add balance_recharge_multiplier system setting (e.g. 1.2 = charge 100 get 120)
- Separate order_amount (credited balance) from pay_amount (actual payment)
- Refund calculates gateway amount proportionally from pay_amount
- Frontend shows both amounts in order details, payment status, refund dialog
- Admin settings UI for configuring recharge multiplier

- Restore gateway_cache.go to upstream (no lua embeds)
- Restore payment_order.go to upstream (use out_trade_no lookup)
- Restore payment_fulfillment.go to upstream (same reason)
- Add FeaturesConfig field and IsWebSearchEmulationEnabled to Channel
- Add applyAccountStatsCost wrapper function
- Add SettingKeyWebSearchEmulationConfig constant
- Add WebSearchEmulationEnabled to SystemSettings
- Add notify code rate limiting methods to EmailCache interface
- Remove AllowUserRefund references (ent schema not present)
- Fix duplicate import in payment_handler.go
- Fix wire_gen.go argument mismatches

Backend fixes:
- #1: doSub subscription idempotency via audit log check
- #2: markFailed only when status=RECHARGING (prevents overwriting COMPLETED)
- #3: ExpireTimedOutOrders checks upstream payment before expiring
- #4: Public verify endpoint for payment result page (no auth required)
- #5: EasyPay QueryOrder returns amount, confirmPayment handles zero amount
- #6: WxPay notifyUrl priority: request-first, config-fallback
- #7: EasyPay remove double URL decode in VerifyNotification
- #8: checkPaid/cancelUpstreamPayment use order's provider instance
- #9: Amount NaN/Inf/negative validation in order creation and refund
- #10: Refund amount comparison uses tolerance instead of float64 ==
- #11: Skip balance deduction on retry when previous rollback failed
- #12: checkPaid logs fulfillment errors instead of silently ignoring
- #13: WxPay certSerial added to required config fields

Frontend fixes:
- Payment result page no longer requires authentication
- Public verify API fallback for expired sessions

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

Tests (1033 new lines, 100% coverage on modified functions):
- amount.go: YuanToFen/FenToYuan with precision edge cases
- wxpay: mapWxState, wxSV, formatPEM, NewWxpay validation
- alipay: isTradeNotExist, NewAlipay validation
- webhook: writeSuccessResponse (wxpay JSON, stripe empty, others text)
- config: validateProviderRequest, isSensitiveConfigField, joinTypes
- fulfillment: resolveRedeemAction idempotency logic

Business logic changes:
- Allow empty supported_types on provider instances
- Block removing payment types when instance has pending orders
- Extract resolveRedeemAction as testable pure function

Backend:
- Extract YuanToFen/FenToYuan to payment/amount.go using shopspring/decimal
- Require alipay publicKey in config validation
- Fix wxpay webhook response to return JSON per V3 spec
- Remove wxpay certSerial fallback to publicKeyId
- Define magic strings as named constants in wxpay/alipay providers
- Add slog warning for wxpay H5→Native payment downgrade
- Make EncryptionKey validation return error on invalid (non-empty) key
- Make decryptConfig propagate errors instead of returning nil
- Add idempotency check in doBalance to prevent stuck FAILED retries

Frontend:
- Fix dashboard currency symbol from $ to ¥
- Fix AdminPaymentPlansView any type to proper SubscriptionPlan type
- Make quick amount buttons follow selected payment method limits
- Center help image with larger height and text below

Add a full payment and subscription system supporting EasyPay (Alipay/WeChat),
Stripe, and direct Alipay/WeChat Pay providers with multi-instance load balancing.