初始化：私有维护版 Gemini-in-Chrome 安装脚本

从 appsail/Gemini-in-Chrome 下载后重写 install.sh / install.ps1：
- 原脚本用正则/sed 做“仅替换已存在字段”，字段本不存在时静默不生效
- 改为 JSON 感知读写（jq 优先，探测/自动装失败时降级为 sed+awk 零依赖兜底）
- 修复过程中实测发现并修掉的坑：BSD sed 不支持 GNU 的 0,/re/ 插入语法、
  正则不容忍冒号后空格导致插入重复 key、macOS 系统自带 bash 3.2 在脚本文件模式下
  中文紧跟未加花括号的 $VAR 会解析错位丢字节
- 新增 test-fixtures/ 下完全人工构造（非真实数据脱敏）的多 profile 测试样本

README.md

@@ -0,0 +1,73 @@
+# Gemini in Chrome
+
+One-click script to enable Chrome's built-in Gemini AI features for non-US users.
+
+## Quick Start
+
+### macOS / Linux
+
+```bash
+curl -fsSL https://raw.githubusercontent.com/appsail/Gemini-in-Chrome/main/install.sh | bash
+```
+
+### Windows
+
+Open PowerShell and run:
+
+```powershell
+irm https://raw.githubusercontent.com/appsail/Gemini-in-Chrome/main/install.ps1 | iex
+```
+
+## What It Does
+
+1. ✅ Checks if Chrome is running (prompts you to close it)
+2. 💾 Backs up your config (`Local State.bak`)
+3. 🔧 Patches these settings:
+   - `is_glic_eligible`: `false` → `true`
+   - `variations_country`: → `us`
+   - `variations_permanent_consistency_country`: → `us`
+4. ✓ Verifies changes were applied
+
+## Restore Original Config
+
+**macOS:**
+```bash
+mv ~/Library/Application\ Support/Google/Chrome/Local\ State.bak \
+   ~/Library/Application\ Support/Google/Chrome/Local\ State
+```
+
+**Linux:**
+```bash
+mv ~/.config/google-chrome/Local\ State.bak \
+   ~/.config/google-chrome/Local\ State
+```
+
+**Windows PowerShell:**
+```powershell
+Move-Item -Path "$env:LOCALAPPDATA\Google\Chrome\User Data\Local State.bak" `
+          -Destination "$env:LOCALAPPDATA\Google\Chrome\User Data\Local State" -Force
+```
+
+## Safety
+
+- Original config is backed up before any changes
+- Only modifies local Chrome settings
+- No data uploaded, no network access (except downloading the script)
+- Easily reversible
+- Unofficial, open source, use at your own risk
+
+## Config Paths
+
+| OS | Path |
+|----|------|
+| macOS | `~/Library/Application Support/Google/Chrome/Local State` |
+| Linux | `~/.config/google-chrome/Local State` |
+| Windows | `%LOCALAPPDATA%\Google\Chrome\User Data\Local State` |
+
+## Issues
+
+Found a bug? [Open an issue](https://github.com/appsail/Gemini-in-Chrome/issues).
+
+## License
+
+MIT