feat(包管理器): 实现LeonOS包管理系统基础功能

添加包管理器核心程序(pkg.lua)及相关支持文件
- 实现包安装、更新、移除、列表、搜索等功能
- 添加包元数据结构和本地存储管理
- 包含示例包和命令补全支持
- 更新系统版本至0.3.0

data/computercraft/lua/rom/packages/example-pkg/1.0.0/completions/example.lua

@@ -0,0 +1,10 @@
+-- example command completion
+
+local shell = require('shell')
+local completion = require('completion')
+
+-- 为example命令设置补全
+shell.setCompletionFunction('example', completion.build({
+  -- 这里可以添加example命令的补全逻辑
+  completion.choice{'--help', '-h'}
+}))

data/computercraft/lua/rom/packages/example-pkg/1.0.0/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "example-pkg",
+  "version": "1.0.0",
+  "description": "An example package for LeonOS",
+  "author": "LeonOS Team",
+  "license": "MIT",
+  "dependencies": {},
+  "files": [
+    "programs/example.lua",
+    "completions/example.lua"
+  ]
+}

data/computercraft/lua/rom/packages/example-pkg/1.0.0/programs/example.lua

@@ -0,0 +1,28 @@
+-- 示例包程序
+local colors = require('colors')
+
+function drawTopBar()
+  local w, h = term.getSize()
+  term.setBackgroundColor(colors.cyan)
+  term.setTextColor(colors.white)
+  term.setCursorPos(1, 1)
+  term.clearLine()
+  local title = "Example Package v1.0.0"
+  local pos = math.floor((w - #title) / 2) + 1
+  term.setCursorPos(pos, 1)
+  term.write(title)
+  term.setBackgroundColor(colors.black)
+  term.setTextColor(colors.white)
+  term.setCursorPos(1, 3)
+end
+
+drawTopBar()
+print("\n这是一个示例包，展示了LeonOS包管理器的功能。")
+print("\n使用方法:")
+print("  pkg install example-pkg  - 安装此包")
+print("  pkg remove example-pkg   - 卸载此包")
+print("  pkg list                 - 列出已安装的包")
+print("\n按任意键退出...")
+os.pullEvent("key")
+term.clear()
+term.setCursorPos(1, 1)