feat(appgui): 添加应用GUI界面支持及包类型管理

新增appgui API用于绘制顶部和底部状态栏，提供一致的UI界面
在package.json中添加type字段区分应用和API包类型
更新安装程序以使用新的appgui界面
修改pkg程序以支持根据包类型安装到不同目录
添加appgui使用文档和演示程序

data/computercraft/lua/rom/programs/appgui_demo.lua

@@ -0,0 +1,64 @@
+-- appgui_demo.lua
+-- Demonstration of the appgui API for drawing top and bottom bars
+
+local appgui = require("appgui")
+local term = require("term")
+local colors = require("colors")
+
+-- Clear the screen before starting
+term.clear()
+
+-- Draw the top bar with default colors (white text on blue background)
+appgui.topbar("LeonOS App GUI Demo")
+
+-- Add some content in the middle
+print()
+print("This is a demonstration of the appgui API.")
+print()
+print("The top bar shows the application title.")
+print("The bottom bar shows the status information.")
+print()
+print("Press any key to see custom colors...")
+
+-- Wait for a key press
+os.pullEvent("key")
+
+-- Clear the screen and redraw with custom colors
+term.clear()
+appgui.topbar("Custom Colored Top Bar", colors.yellow, colors.red)
+
+-- Add some content
+print()
+print("Now with custom colors!")
+print()
+print("Top bar: Yellow text on Red background")
+print()
+print("Press any key to continue...")
+
+-- Wait for a key press
+os.pullEvent("key")
+
+-- Clear the screen and draw both top and bottom bars
+term.clear()
+appgui.topbar("Complete GUI Demo")
+appgui.downbar("Status: Running - Press Q to quit")
+
+-- Add some content in the middle
+print()
+print("Now you can see both top and bottom bars.")
+print()
+print("Try resizing the terminal window to see how the text stays centered.")
+print()
+print("Press Q to exit this demo.")
+
+-- Main loop to handle key presses
+while true do
+  local event, key = os.pullEvent("key")
+  if key == 16 then -- Q key
+    break
+  end
+end
+
+-- Clear the screen before exiting
+term.clear()
+print("AppGUI Demo has ended.")