Fix missing config handling and auto-restart after setup

cmd/qfs/main.go

@@ -2,8 +2,10 @@ package main
 
 import (
 	"context"
+	"errors"
 	"flag"
 	"fmt"
+	"io/fs"
 	"log/slog"
 	"net/http"
 	"os"
@@ -88,7 +90,7 @@ func main() {
 	// Load config for server settings (optional)
 	cfg, err := config.Load(*configPath)
 	if err != nil {
-		if os.IsNotExist(err) {
+		if errors.Is(err, fs.ErrNotExist) {
 			// Use defaults if config file doesn't exist
 			slog.Info("config file not found, using defaults", "path", *configPath)
 			cfg = &config.Config{}