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/payment_start.go

@@ -60,11 +60,6 @@ func (r *Repository) Start(ctx context.Context, userID uint64, orderID uint64, r
 		return nil, ErrPaymentUnavailable
 	}
 
-	r.log().Info("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) Start(ctx context.Context, userID uint64, orderID uint64, r
 	})
 	if err != nil {
 		_ = r.markPaymentFailed(ctx, payment.ID, nil, err.Error())
-		r.log().Warn("payment request failed", paymentLogFields(ctx, appendFields(
+		r.log().Warn("支付下单请求失败", paymentLogFields(ctx, appendFields(
 			paymentOrderFields(payment),
 			runtimeConfigFields(runtimeConfig),
 			[]zap.Field{zap.Error(err)},
@@ -88,7 +83,7 @@ func (r *Repository) Start(ctx context.Context, userID uint64, orderID uint64, r
 	}
 	if !resp.OK {
 		_ = r.markPaymentFailed(ctx, payment.ID, resp.Raw, resp.ErrorMessage)
-		r.log().Warn("payment rejected", paymentLogFields(ctx, appendFields(
+		r.log().Warn("支付下单被渠道拒绝", paymentLogFields(ctx, appendFields(
 			paymentOrderFields(payment),
 			runtimeConfigFields(runtimeConfig),
 			[]zap.Field{
@@ -117,7 +112,7 @@ func (r *Repository) Start(ctx context.Context, userID uint64, orderID uint64, r
 		return nil, err
 	}
 	r.recordConfigUsage(ctx, runtimeConfig, latest)
-	r.log().Info("payment result", paymentLogFields(ctx, appendFields(
+	r.log().Info("支付下单完成", paymentLogFields(ctx, appendFields(
 		paymentOrderFields(latest),
 		runtimeConfigFields(runtimeConfig),
 	)...,