Originally Posted by
Koyote
Get some MTB shoes and pedals.
OP's pic seems to show MTB shoes, albeit with minimal tread blocks.
If those aren't enough, maybe go for a fuller sole, which tends to be common on touring or commuter shoes, and sometimes lower end MTB shoes. They will be more flexible and heavier though, so if you don't want that go with Koyote's suggestion and remove your shoes for the stair climb.