fix(agent/windows): named pipe Tailscale + hideWindow + logs

- Use Windows named pipe \.\pipe\studioe5-tailscaled instead of Unix socket
- Apply hideWindow to all child processes (tailscale, podman, docker, browser)
- Redirect agent logs to <data-dir>/agent.log and tailscaled logs to tailscaled.log
- Fix double tailscale/ tailscale dir path in startTailscaleAndReport
- Remove --operator=root on Windows
- Bump agent version to 0.3.1

agent/systray.go

@@ -80,7 +80,9 @@ func openBrowser(url string) {
 		args = []string{url}
 	}
 
-	if err := exec.Command(cmd, args...).Start(); err != nil {
+	openCmd := exec.Command(cmd, args...)
+	hideWindow(openCmd)
+	if err := openCmd.Start(); err != nil {
 		log.Printf("Failed to open browser: %v", err)
 	}
 }