[Demo] Add hello_demo() function to demo_output.py

[GlacierEQ]

Goal

Create a file called demo_output.py in the repository root with a single function:

def hello_demo():
    return "Hello from Agent OS!"

if __name__ == "__main__":
    print(hello_demo())

Success Criteria

• File demo_output.py exists in the repo root
• Contains the hello_demo() function that returns the greeting string
• File is executable with python3 demo_output.py

Constraints

• Single file, no dependencies
• Prefer minimal diffs