feat(pkg): 更新包管理系统并升级至LeonOS 0.3.6

- 将包安装目录从/leonos/packages迁移至/packages
- 更新版本号至0.3.6
- 修改installer.lua以正确处理packages目录
- 更新pkg.lua程序适配新的包路径
- 添加示例包文件到新位置

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

@@ -0,0 +1,25 @@
+-- Example Package Program
+local colors = require('colors')
+local term = require('term')
+
+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("\nThis is an example package that demonstrates the features of LeonOS package manager.")
+print("\nUsage:")
+print("  pkg install example-pkg  - Install this package")
+print("  pkg remove example-pkg   - Uninstall this package")
+print("  pkg list                 - List installed packages")