chore(dev): give dev builds their own userData and single-instance lock

A dev instance shared the installed build's userData directory and lock, so
starting it demanded killing the real app and it wrote test settings and
session snapshots into the live profile. Dev now uses OpenTerminal-dev and
tags its window title '(dev)'; both instances run side by side.

AGENTS.md

@@ -5,6 +5,7 @@ Electron + electron-vite + React 终端工具（本地终端 / SSH / SFTP）。
 ## 常用命令
 
 - 开发：`npm run dev`（主进程改动不热重建，需重启）
+- dev 实例使用独立用户数据目录 `%APPDATA%\OpenTerminal-dev` 与独立单实例锁（`src/main/index.ts` 顶部 `!app.isPackaged` 分支），窗口标题带 `(dev)`：**可与已安装的正式版同时运行，互不干扰**，也不会把测试设置/会话写进真实配置
 - 类型检查：`npx tsc --noEmit -p tsconfig.web.json`
 - 打包：`npm run dist`，产物在 `release/`（msi + exe + latest.yml + blockmap）
   - 国内网络需镜像：`ELECTRON_MIRROR=https://npmmirror.com/mirrors/electron/ ELECTRON_BUILDER_BINARIES_MIRROR=https://npmmirror.com/mirrors/electron-builder-binaries/ npm run dist`