refactor(core,shim): 统一基于 thiserror 的错误体系

- 移除 anyhow，使用 thiserror 定义强类型 Error 枚举
- 支持 #[from] 自动转换 mlua::Error，关键路径保留源码与上下文
- LuaRuntimeBuilder 采用惰性错误收集，简化链式初始化调用
- MirrorRegistry 实现规范化 FromLuaConversionError 错误转换

commands/commands.lua

@@ -1,37 +1,27 @@
 -- commands/commands.lua
-function command(mod_path)
-    -- 无论输入 "a/b/c" 还是 "a\b\c"，统一替换为标准的 "a.b.c"
-    local normalized = mod_path:gsub("[/\\]", ".")
-
-    return {
-        __is_lazy_command = true,
-        module = normalized
-    }
-end
-
 
 return {
     -- 1. 单文件子命令 (commands/use.lua)
     ["use"] = {
         description = "Switch the active version of a tool",
-        handler = command("use")
+        module = mr.command("use")
     },
 
     -- 2. 单文件子命令 (commands/list.lua)
     ["list"] = {
         description = "List available and currently activated versions",
-        handler = command("list")
+        module = mr.command("list")
     },
 
     -- 3. 复杂多文件子命令 (加载 commands/log/init.lua)
     ["log"] = {
         description = "View or configure mirror runtime logs",
-        handler = command("log")
+        module = mr.command("log")
     },
 
     -- 4. 支持别名快捷映射 (例如 mr ls 等价于 mr list)
     ["ls"] = {
         description = "Alias for list",
-        handler = command("list")
+        module = mr.command("list")
     }
 }