Add structured logging with zerolog

- Implement zerolog logger package with configurable levels
- Add contextual logging middleware (request_id, user_id, method, path, status, duration)
- Support both JSON (production) and human-readable (development) formats
- Add LOG_LEVEL and ENVIRONMENT configuration variables
- Replace standard log calls with structured logger throughout application
- Integrate logger in HTTP router and auth middleware

internal/infrastructure/logger/logger.go

@@ -0,0 +1,90 @@
+package logger
+
+import (
+	"io"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/pkgerrors"
+)
+
+var Log zerolog.Logger
+
+type Config struct {
+	Level       string
+	Environment string
+}
+
+func Init(config Config) {
+	zerolog.ErrorStackMarshaler = pkgerrors.MarshalStack
+	zerolog.TimeFieldFormat = time.RFC3339
+
+	level := parseLogLevel(config.Level)
+	zerolog.SetGlobalLevel(level)
+
+	var output io.Writer = os.Stdout
+
+	if config.Environment == "development" {
+		output = zerolog.ConsoleWriter{
+			Out:        os.Stdout,
+			TimeFormat: "15:04:05",
+			NoColor:    false,
+		}
+	}
+
+	Log = zerolog.New(output).
+		With().
+		Timestamp().
+		Caller().
+		Logger()
+
+	Log.Info().
+		Str("level", level.String()).
+		Str("environment", config.Environment).
+		Msg("Logger initialized")
+}
+
+func parseLogLevel(level string) zerolog.Level {
+	switch strings.ToLower(level) {
+	case "debug":
+		return zerolog.DebugLevel
+	case "info":
+		return zerolog.InfoLevel
+	case "warn", "warning":
+		return zerolog.WarnLevel
+	case "error":
+		return zerolog.ErrorLevel
+	case "fatal":
+		return zerolog.FatalLevel
+	case "panic":
+		return zerolog.PanicLevel
+	default:
+		return zerolog.InfoLevel
+	}
+}
+
+func Debug() *zerolog.Event {
+	return Log.Debug()
+}
+
+func Info() *zerolog.Event {
+	return Log.Info()
+}
+
+func Warn() *zerolog.Event {
+	return Log.Warn()
+}
+
+func Error() *zerolog.Event {
+	return Log.Error()
+}
+
+func Fatal() *zerolog.Event {
+	return Log.Fatal()
+}
+
+func With() zerolog.Context {
+	return Log.With()
+}