refactor: 提取 core 库 + 新增 CLI 版本

- 创建 Cargo workspace（core / src-tauri / cli 三 crate）
- core: 纯 Rust 库，零 Tauri 依赖，包含所有业务逻辑
- src-tauri/commands: 改为薄包装，调用 core 函数
- cli: 基于 clap 的命令行工具，支持 JSON 输出
- CLI 命令: list, add, remove, conflicts, scan, profile, check-admin

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

core/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "path-editor-core"
+version = "5.0.0"
+description = "PathEditor core library — shared between GUI and CLI"
+authors = ["刘航宇"]
+license = "MIT"
+edition = "2021"
+
+[dependencies]
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+log = "0.4"
+winreg = "0.52"
+dirs = "5"
+chrono = "0.4"