Enhance build system and logging configuration

- Add scripts/build.sh to compile binaries into bin/ directory

- Move all zerolog setup logic from cmd/server/main.go to pkg/config

- Add log level configuration support (trace, debug, info, warn, error, fatal, panic)

- Simplify cmd/server/main.go from 57 to 27 lines (53% reduction)

- Update .gitignore to use bin/ directory instead of individual files

- Document build process and bin directory in AGENTS.md

- Maintain backward compatibility with all existing functionality

pkg/config/config.go

@@ -3,8 +3,10 @@ package config
 import (
 	"fmt"
 	"os"
+	"strings"
 	"time"
 
+	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
 	"github.com/spf13/viper"
 )
@@ -30,7 +32,8 @@ type ShutdownConfig struct {
 
 // LoggingConfig holds logging-related configuration
 type LoggingConfig struct {
-	JSON bool `mapstructure:"json"`
+	JSON    bool   `mapstructure:"json"`
+	Level   string `mapstructure:"level"`
 }
 
 // TelemetryConfig holds OpenTelemetry-related configuration
@@ -53,12 +56,17 @@ type SamplerConfig struct {
 // To specify a custom config file path, set DLC_CONFIG_FILE environment variable
 func LoadConfig() (*Config, error) {
 	v := viper.New()
+	
+	// Set up initial console logging for config loading messages
+	consoleWriter := zerolog.ConsoleWriter{Out: os.Stderr}
+	log.Logger = log.Output(consoleWriter)
 
 	// Set default values
 	v.SetDefault("server.host", "0.0.0.0")
 	v.SetDefault("server.port", 8080)
 	v.SetDefault("shutdown.timeout", 30*time.Second)
 	v.SetDefault("logging.json", false)
+	v.SetDefault("logging.level", "trace")
 
 	// Telemetry defaults
 	v.SetDefault("telemetry.enabled", false)
@@ -97,6 +105,7 @@ func LoadConfig() (*Config, error) {
 	v.BindEnv("server.port", "DLC_SERVER_PORT")
 	v.BindEnv("shutdown.timeout", "DLC_SHUTDOWN_TIMEOUT")
 	v.BindEnv("logging.json", "DLC_LOGGING_JSON")
+	v.BindEnv("logging.level", "DLC_LOGGING_LEVEL")
 
 	// Telemetry environment variables
 	v.BindEnv("telemetry.enabled", "DLC_TELEMETRY_ENABLED")
@@ -113,11 +122,23 @@ func LoadConfig() (*Config, error) {
 		return nil, fmt.Errorf("config unmarshal error: %w", err)
 	}
 
+	// Configure log output format (JSON or console) first
+	if config.Logging.JSON {
+		log.Logger = log.Output(os.Stderr)
+	} else {
+		consoleWriter := zerolog.ConsoleWriter{Out: os.Stderr}
+		log.Logger = log.Output(consoleWriter)
+	}
+
+	// Setup logging based on configuration
+	config.SetupLogging()
+
 	log.Info().
 		Str("host", config.Server.Host).
 		Int("port", config.Server.Port).
 		Dur("shutdown_timeout", config.Shutdown.Timeout).
 		Bool("logging_json", config.Logging.JSON).
+		Str("logging_level", config.Logging.Level).
 		Bool("telemetry_enabled", config.Telemetry.Enabled).
 		Str("telemetry_service", config.Telemetry.ServiceName).
 		Msg("Configuration loaded")
@@ -159,3 +180,40 @@ func (c *Config) GetSamplerType() string {
 func (c *Config) GetSamplerRatio() float64 {
 	return c.Telemetry.Sampler.Ratio
 }
+
+// GetLogLevel returns the logging level
+func (c *Config) GetLogLevel() string {
+	return c.Logging.Level
+}
+
+// SetupLogging configures zerolog based on the configuration
+func (c *Config) SetupLogging() {
+	// Parse log level
+	level := parseLogLevel(c.GetLogLevel())
+	zerolog.SetGlobalLevel(level)
+	
+	zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
+}
+
+// parseLogLevel converts a string log level to zerolog.Level
+func parseLogLevel(level string) zerolog.Level {
+	switch strings.ToLower(level) {
+	case "trace":
+		return zerolog.TraceLevel
+	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:
+		log.Warn().Str("level", level).Msg("Unknown log level, defaulting to trace")
+		return zerolog.TraceLevel
+	}
+}