feat(cli): 优化 log 子命令并引入 LogLevel 强类型解析,重构 commands.lua 注册表解析与校验逻辑

- 调整 LogLevel 的 FromStr 错误类型为 String，适配 clap 的 value_parser
- log 子命令直接绑定 LogLevel 枚举，消除硬编码校验与类型转换
- 规范化日志级别更新与配置读取逻辑
- handler 类型有 Function 改为 String

commands/commands.lua

@@ -0,0 +1,37 @@
+-- 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")
+    },
+
+    -- 2. 单文件子命令 (commands/list.lua)
+    ["list"] = {
+        description = "List available and currently activated versions",
+        handler = 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")
+    },
+
+    -- 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")
+    }
+}

commands/log/init.lua

@@ -0,0 +1,24 @@
+-- commands/log/init.lua
+local argparse = require("argparse")
+local utils = require("log.utils") -- 支持相对目录级 require
+
+return function(raw_args)
+    local parser = argparse("mr log", "Manage and view mirror logs.")
+    parser:option("-l --level", "Set log level"):choices({"trace", "debug", "info", "warn", "error"})
+    parser:option("-t --tail", "Show last N lines"):convert(tonumber)
+
+    local ok, args = pcall(function() return parser:parse(raw_args) end)
+    if not ok then
+        error("__ARGPARSE_HELP__")
+    end
+
+    if args.level then
+        print(utils.format_level(args.level))
+        mr.fs.write(__MIRROR_DIR__ .. "/mirror-log.ini", "level = \"" .. args.level .. "\"\n")
+        print("✔ Updated log level.")
+    elseif args.tail then
+        print(string.format("Tailing last %d lines...", args.tail))
+    else
+        print("Log module ready. Run 'mr log --help' for details.")
+    end
+end

commands/log/utils.lua

@@ -0,0 +1,8 @@
+-- commands/log/utils.lua
+local M = {}
+
+function M.format_level(level)
+    return string.format("==> [LOG LEVEL: %s] <==", string.upper(level))
+end
+
+return M