If you did not have any income sourced from the state you moved to after 12/11/2024 to 12/31/2024, then use Colorado as your state of residence for 2024.
It depends. Residency is established through driver's license, voting, intent to be a resident, etc. We don't know if you vacationed with friends the rest of December or changed everything to a new state. You could have moved somewhere to decide if you wanted to live there. You could be a nonresident somewhere new.
You could be part year resident or full year.
Here are some things states look at when determining residency from The Tax Book: