feat(帮助系统): 添加helplist命令用于列出所有帮助主题

添加helplist.lua程序用于列出所有可用的帮助主题，支持排序和彩色输出选项
同时添加test_helplist.lua测试脚本验证helplist命令功能

data/computercraft/lua/rom/programs/test_helplist.lua

@@ -0,0 +1,63 @@
+-- test_helplist.lua: Test the helplist command
+local shell = require("shell")
+local term = require("term")
+
+print("=== Testing helplist Command ===")
+print("This test will run the helplist command with different options")
+print("to verify it correctly lists all available help topics.")
+print("
+Test 1: Basic helplist command")
+os.sleep(1)
+term.clear()
+local success = shell.run("helplist")
+if not success then
+  print("Error: helplist command failed to run.")
+else
+  print("
+Test 1 completed. Press any key to continue.")
+os.pullEvent("key")
+end
+
+print("
+Test 2: helplist with sorting")
+os.sleep(1)
+term.clear()
+success = shell.run("helplist", "--sort")
+if not success then
+  print("Error: helplist --sort command failed to run.")
+else
+  print("
+Test 2 completed. Press any key to continue.")
+os.pullEvent("key")
+end
+
+print("
+Test 3: helplist with color")
+os.sleep(1)
+term.clear()
+success = shell.run("helplist", "--color")
+if not success then
+  print("Error: helplist --color command failed to run.")
+else
+  print("
+Test 3 completed. Press any key to continue.")
+os.pullEvent("key")
+end
+
+print("
+Test 4: helplist help")
+os.sleep(1)
+term.clear()
+success = shell.run("helplist", "--help")
+if not success then
+  print("Error: helplist --help command failed to run.")
+else
+  print("
+Test 4 completed. Press any key to finish.")
+os.pullEvent("key")
+end
+
+term.clear()
+print("=== helplist Command Tests Completed ===")
+print("All tests have been executed.")
+print("You can now use the 'helplist' command to list all available help topics.")