While you can't guarantee it being 100% safe, I'd say you're okay as long as you wash the vegetables thoroughly - there should be no direct contact between the edible part and the cat poo after all.

Bark mulch is not great for veggies. Use a thick layer of straw instead. Put it down now and the cats won't bother with it again. If you can't mulch immediately, cover the bed with sharp twigs or sticks poked vertically into the soil at close intervals.

It is a little late for planting spinach in Ontario. If you must plant spinach, plant a bolt-resistant variety like Tyee. You will have better luck planting it again in mid August for a fall harvest.

A little late? We've had temps below freezing here these past couple of weeks overnight.

Doesn't matter. Spinach can tolerate temperatures down to -10 degrees C. The really long daylight hours in Canada trigger bolting faster than in the U.S, so the earlier you can get it in the ground the longer the spring harvest window will be.

Do not worry about the cats. I have three that use the garden often.

I have had cats peeing and pooping in my gardens for as many decades as I have been gardening and except for I now have a desire for catnip, nothing is wrong.

I'm pretty casual about pathogens and parasite eggs, but I'd try and avoid them in my garden.
My big issue is...cat poo stinks and I don't want it on my hands!
I wouldn't use wood on the vege garden: I'd inevitably mix it into the soil and have all sorts of nitrogen issues.
I use mainly dried lawn clippings, leaves and occasionally straw for mulch.