重构日志与可观测性体系

新增单行文本编码器与结构化 GORM 日志，统一错误记录与请求日志策略，收紧日志文件权限并修复按天切分与压缩，支付回调参数脱敏，生产强制阿里云短信，RequestID 校验防注入，日志文案中文化。

backend/internal/modules/payment/mohong_payment.go

@@ -60,11 +60,6 @@ func (r *Repository) StartMohong(ctx context.Context, userID uint64, orderID uin
 		return nil, ErrPaymentUnavailable
 	}
 
-	r.log().Info("mohong payment start", paymentLogFields(ctx, appendFields(
-		paymentOrderFields(payment),
-		runtimeConfigFields(runtimeConfig),
-	)...,
-	)...)
 	resp, err := runtimeConfig.Channel.CreatePayment(ctx, channelCreatePaymentRequest{
 		ThirdOrderID: payment.ThirdOrderID,
 		AmountCent:   payment.AmountCent,
@@ -78,7 +73,7 @@ func (r *Repository) StartMohong(ctx context.Context, userID uint64, orderID uin
 	})
 	if err != nil {
 		_ = r.markPaymentFailed(ctx, payment.ID, nil, err.Error())
-		r.log().Warn("mohong payment request failed", paymentLogFields(ctx, appendFields(
+		r.log().Warn("魔哄支付下单失败", paymentLogFields(ctx, appendFields(
 			paymentOrderFields(payment),
 			runtimeConfigFields(runtimeConfig),
 			[]zap.Field{zap.Error(err)},
@@ -107,6 +102,11 @@ func (r *Repository) StartMohong(ctx context.Context, userID uint64, orderID uin
 		return nil, err
 	}
 	r.recordConfigUsage(ctx, runtimeConfig, latest)
+	r.log().Info("魔哄支付下单完成", paymentLogFields(ctx, appendFields(
+		paymentOrderFields(latest),
+		runtimeConfigFields(runtimeConfig),
+	)...,
+	)...)
 	dto := toDTO(*latest)
 	return &dto, nil
 }