Replace zerolog with log/slog from stdlib

- Rewrite logger package to use slog with LevelVar for dynamic levels
- Update all packages to use *slog.Logger instead of *zerolog.Logger
- Use TextHandler for TTY (dev), JSONHandler for production
- Add make check target (runs lint + test)
- Add make test target

internal/config/config.go

@@ -2,10 +2,10 @@ package config
 
 import (
 	"fmt"
+	"log/slog"
 
 	"git.eeqj.de/sneak/gohttpserver/internal/globals"
 	"git.eeqj.de/sneak/gohttpserver/internal/logger"
-	"github.com/rs/zerolog"
 	"github.com/spf13/viper"
 	"go.uber.org/fx"
 
@@ -37,7 +37,7 @@ type Config struct {
 	Port             int
 	SentryDSN        string
 	params           *ConfigParams
-	log              *zerolog.Logger
+	log              *slog.Logger
 }
 
 func New(lc fx.Lifecycle, params ConfigParams) (*Config, error) {
@@ -69,9 +69,8 @@ func New(lc fx.Lifecycle, params ConfigParams) (*Config, error) {
 			// Config file not found; ignore error if desired
 		} else {
 			// Config file was found but another error was produced
-			log.Panic().
-				Err(err).
-				Msg("config file malformed")
+			log.Error("config file malformed", "error", err)
+			panic(err)
 		}
 	}