Stroller and stairs

I have an issue and coming to you guys to see if you have any ideas or tips. Baby is 6 months old and to take her anywhere we have always put her in her car seat in the house and carried her down the stairs and put it on the stroller to take her on a walk. Now that shes bigger shes been cranking her head to see out so we put her in the uppababy cruz seat and she likes it! baby is also too heavy now to carry up and down the stairs in the carseat.

Sooo,, How do you guys get babe downstairs without putting them in the car seat?

My garage is not automatic, its very heavy to open so need two hands.

Two, I do not want to keep the stroller with the seat in the garage as there are many centipedes, rats, and spiders where I live.

I go on a walk everyday, as baby loves it and it keeps me sane as a mom who works from home.

any ideas??