在编辑 UTF-8BOM 编码的文件时,会在前面重复添加乱码

Issue Description

Steps to Reproduce

代码文件是 UTF-8 BOM 编码时,让 AI 修改 C++ / xmake.lua 等文件时,有概率在文件开头出现几个筹码字符。

Expected Behavior

不要乱码

Actual Behavior

Screenshots / Screen Recordings

Operating System

Windows 10

Current Qoder Version (Menu → About Qoder → Copy)

Version: 0.1.19
VSCode Version: 1.100.0 (user setup)
Commit: 81b1462db5734d6b9797b4d97ac6d5b47559d83c
Date: 2025-08-29T15:18:17.700Z
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.19045

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