refactor: 后端日志系统重构

- 新增模块化日志器（pkg/logger/module.go）
- 新增 GORM 日志适配器
- 统一日志入口，移除所有 zap.L() 全局 logger 调用
- 字段标准化
- 启动阶段使用结构化日志
- 更新所有相关测试

backend/pkg/logger/gorm.go

@@ -0,0 +1,130 @@
+package logger
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"regexp"
+	"strings"
+	"time"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+	"gorm.io/gorm"
+	gormlogger "gorm.io/gorm/logger"
+)
+
+type GormLogger struct {
+	logger *zap.Logger
+	level  zapcore.Level
+}
+
+func NewGormLogger(logger *zap.Logger) *GormLogger {
+	return &GormLogger{
+		logger: logger.Named("database"),
+		level:  zapcore.DebugLevel,
+	}
+}
+
+func (l *GormLogger) LogMode(level gormlogger.LogLevel) gormlogger.Interface {
+	newLogger := &GormLogger{
+		logger: l.logger,
+		level:  l.gormLevelToZap(level),
+	}
+	return newLogger
+}
+
+func (l *GormLogger) Info(ctx context.Context, msg string, data ...interface{}) {
+	if l.level > zapcore.DebugLevel {
+		return
+	}
+	l.log(ctx, zapcore.DebugLevel, msg, data...)
+}
+
+func (l *GormLogger) Warn(ctx context.Context, msg string, data ...interface{}) {
+	if l.level > zapcore.WarnLevel {
+		return
+	}
+	l.log(ctx, zapcore.WarnLevel, msg, data...)
+}
+
+func (l *GormLogger) Error(ctx context.Context, msg string, data ...interface{}) {
+	if l.level > zapcore.ErrorLevel {
+		return
+	}
+	l.log(ctx, zapcore.ErrorLevel, msg, data...)
+}
+
+func (l *GormLogger) Trace(ctx context.Context, begin time.Time, fc func() (string, int64), err error) {
+	if l.level > zapcore.DebugLevel {
+		return
+	}
+
+	elapsed := time.Since(begin)
+	sql, rows := fc()
+
+	fields := []zap.Field{
+		zap.String("sql", l.formatSQL(sql)),
+		zap.Int64("rows", rows),
+		zap.Duration("latency", elapsed),
+	}
+
+	if requestIDField := RequestIDFromContext(ctx); requestIDField != zap.Skip() {
+		fields = append([]zap.Field{requestIDField}, fields...)
+	}
+
+	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
+		fields = append(fields, zap.Error(err))
+		l.logger.Error("SQL执行错误", fields...)
+		return
+	}
+
+	l.logger.Debug("SQL查询", fields...)
+}
+
+func (l *GormLogger) log(ctx context.Context, level zapcore.Level, msg string, data ...interface{}) {
+	fields := make([]zap.Field, 0, len(data)/2+1)
+
+	if requestIDField := RequestIDFromContext(ctx); requestIDField != zap.Skip() {
+		fields = append(fields, requestIDField)
+	}
+
+	for i := 0; i < len(data); i += 2 {
+		if i+1 < len(data) {
+			key, ok := data[i].(string)
+			if !ok {
+				continue
+			}
+			fields = append(fields, zap.Any(key, data[i+1]))
+		}
+	}
+
+	switch level {
+	case zapcore.DebugLevel:
+		l.logger.Debug(fmt.Sprintf(msg, data...), fields...)
+	case zapcore.WarnLevel:
+		l.logger.Warn(fmt.Sprintf(msg, data...), fields...)
+	case zapcore.ErrorLevel:
+		l.logger.Error(fmt.Sprintf(msg, data...), fields...)
+	}
+}
+
+func (l *GormLogger) gormLevelToZap(level gormlogger.LogLevel) zapcore.Level {
+	switch level {
+	case gormlogger.Silent:
+		return zapcore.PanicLevel
+	case gormlogger.Error:
+		return zapcore.ErrorLevel
+	case gormlogger.Warn:
+		return zapcore.WarnLevel
+	case gormlogger.Info:
+		return zapcore.DebugLevel
+	default:
+		return zapcore.DebugLevel
+	}
+}
+
+func (l *GormLogger) formatSQL(sql string) string {
+	re := regexp.MustCompile(`\s+`)
+	return strings.TrimSpace(re.ReplaceAllString(sql, " "))
+}