fix: replace non-existent log package with stdlib slog

The log package was imported but never existed in the repo, causing
golangci-lint to fail with "no export data" error. Use slog.NewTextHandler
from stdlib instead.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ysyneu

cmd/main.go

@@ -13,7 +13,6 @@ import (
 
 	"github.com/spf13/cobra"
 
-	"github.com/flashcatcloud/flashduty-runner/log"
 	"github.com/flashcatcloud/flashduty-runner/permission"
 	"github.com/flashcatcloud/flashduty-runner/workspace"
 	"github.com/flashcatcloud/flashduty-runner/ws"
@@ -244,7 +243,7 @@ func runRunner() error {
 func setupLogging(levelStr string) {
 	level := parseLogLevel(levelStr)
 	opts := &slog.HandlerOptions{Level: level}
-	handler := log.NewOrderedTextHandler(os.Stdout, opts)
+	handler := slog.NewTextHandler(os.Stdout, opts)
 	slog.SetDefault(slog.New(handler))
 }