Add MacroCommand demo to Command Pattern

[darbyluv2code]

Summary

• Add MacroCommand class that groups multiple SmartHomeCommand objects into a named scene
• Executes commands in order, undoes them in reverse (LIFO)
• Update MainApp with runMacroCommandDemo() showing a "Good Morning" scene

Test plan

• Review MacroCommand.java implements SmartHomeCommand correctly
• Verify MainApp compiles and runMacroCommandDemo() runs without errors
• Confirm undo reverses all commands in the correct order