feat: 添加 zap 日志工厂和 GORM 日志桥接

- NewLogger 工厂函数：支持 JSON/Console 编码、stdout/文件/多输出、lumberjack 轮转

- NewGormLogger 实现 gorm.Interface：Trace 区分错误/慢查询/正常查询

- output_stdout 用 *bool 三态处理（nil=true, true, false）

- 默认值：level=info, encoding=json, max_size=100, max_backups=5, max_age=30

- 慢查询阈值 200ms，ErrRecordNotFound 不视为错误

- 编译时接口检查: var _ gormlogger.Interface = (*GormLogger)(nil)

- 完整 TDD 测试覆盖

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/logger/gorm.go

@@ -0,0 +1,148 @@
+package logger
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+	"gorm.io/gorm"
+	gormlogger "gorm.io/gorm/logger"
+)
+
+const slowQueryThreshold = 200 * time.Millisecond
+
+// GormLogger implements gorm's logger.Interface backed by zap.
+type GormLogger struct {
+	logger *zap.Logger
+	level  zapcore.Level
+	silent bool
+}
+
+// Compile-time interface check.
+var _ gormlogger.Interface = (*GormLogger)(nil)
+
+// NewGormLogger creates a new GormLogger wrapping the given zap logger.
+// The level string maps to zap levels; empty defaults to "warn".
+// The special value "silent" suppresses all output.
+func NewGormLogger(zapLogger *zap.Logger, level string) gormlogger.Interface {
+	lvl := parseGormLevel(level)
+	silent := level == "silent"
+	return &GormLogger{
+		logger: zapLogger,
+		level:  lvl,
+		silent: silent,
+	}
+}
+
+// LogMode returns a new GormLogger with the given gorm log level.
+// It does NOT mutate the receiver.
+func (l *GormLogger) LogMode(level gormlogger.LogLevel) gormlogger.Interface {
+	newLogger := &GormLogger{
+		logger: l.logger,
+		level:  l.level,
+		silent: l.silent,
+	}
+
+	switch level {
+	case gormlogger.Silent:
+		newLogger.silent = true
+	case gormlogger.Error:
+		newLogger.level = zapcore.ErrorLevel
+		newLogger.silent = false
+	case gormlogger.Warn:
+		newLogger.level = zapcore.WarnLevel
+		newLogger.silent = false
+	case gormlogger.Info:
+		newLogger.level = zapcore.InfoLevel
+		newLogger.silent = false
+	}
+
+	return newLogger
+}
+
+// Info logs at zap.InfoLevel with structured fields from key-value pairs.
+func (l *GormLogger) Info(ctx context.Context, msg string, args ...any) {
+	if l.silent || l.level > zapcore.InfoLevel {
+		return
+	}
+	l.logger.Info(msg, argsToFields(args)...)
+}
+
+// Warn logs at zap.WarnLevel with structured fields from key-value pairs.
+func (l *GormLogger) Warn(ctx context.Context, msg string, args ...any) {
+	if l.silent || l.level > zapcore.WarnLevel {
+		return
+	}
+	l.logger.Warn(msg, argsToFields(args)...)
+}
+
+// Error logs at zap.ErrorLevel with structured fields from key-value pairs.
+func (l *GormLogger) Error(ctx context.Context, msg string, args ...any) {
+	if l.silent || l.level > zapcore.ErrorLevel {
+		return
+	}
+	l.logger.Error(msg, argsToFields(args)...)
+}
+
+// Trace logs SQL query information based on execution results.
+func (l *GormLogger) Trace(ctx context.Context, begin time.Time, fc func() (sql string, rowsAffected int64), err error) {
+	if l.silent {
+		return
+	}
+
+	elapsed := time.Since(begin)
+	sql, rows := fc()
+
+	switch {
+	case err != nil && !errors.Is(err, gorm.ErrRecordNotFound):
+		l.logger.Error("gorm query error",
+			zap.Error(err),
+			zap.String("sql", sql),
+			zap.Int64("rows", rows),
+			zap.Duration("elapsed", elapsed),
+		)
+	case elapsed > slowQueryThreshold:
+		l.logger.Warn("gorm slow query",
+			zap.String("sql", sql),
+			zap.Int64("rows", rows),
+			zap.Float64("elapsed_ms", float64(elapsed.Nanoseconds())/1e6),
+		)
+	default:
+		if l.level > zapcore.InfoLevel {
+			return
+		}
+		l.logger.Info("gorm query",
+			zap.String("sql", sql),
+			zap.Int64("rows", rows),
+			zap.Duration("elapsed", elapsed),
+		)
+	}
+}
+
+// parseGormLevel parses a level string into a zapcore.Level.
+// Defaults to zapcore.WarnLevel.
+func parseGormLevel(level string) zapcore.Level {
+	if level == "" || level == "silent" {
+		return zapcore.WarnLevel
+	}
+	var lvl zapcore.Level
+	if err := lvl.UnmarshalText([]byte(level)); err != nil {
+		return zapcore.WarnLevel
+	}
+	return lvl
+}
+
+// argsToFields converts alternating key-value pairs into zap fields.
+func argsToFields(args []any) []zap.Field {
+	fields := make([]zap.Field, 0, len(args)/2)
+	for i := 0; i+1 < len(args); i += 2 {
+		key, ok := args[i].(string)
+		if !ok {
+			continue
+		}
+		fields = append(fields, zap.Any(key, args[i+1]))
+	}
+	return fields
+}