Pretty much all solanum leaves can be forked. Those look perfectly healthy to me. Look for gnarled, cupped, distorted leaves.

Standard cheap test for herbicides is a bioassay. Takes a few weeks. Take the soil you want to test in one container, and soil they you're confident is herbicide free in another. (Actually, if you mix activated charcoal in the latter, it will inactivate most soil-borne herbicides.) Plant a half dozen bean seeds in each container. Look for those signs in the test soil.

Foliage is completely normal for a Brandywine, which is a potato leaf variety of tomato.

That's just the way they grow. They look very healthy. Herbicide damage would result in twisted curled leaves.

Not all herbicide causes cupping, curling, twisting growth, that is a result typically seen in growth regulator herbicides like 2, 4-d (which isn’t considered a persistent herbicide). Something like Glyphosate, an amino acid inhibitor, simply causes some leaf yellowing and then death. Glyphosate is not a persistent herbicide, either.

The biggest concern that I know of for persistent herbicide, particularly in manure, is Aminopyralid which often causes EXTREME curling of the new growth on affected plants, like the leaves are making a tight fist or have been rolled into little balls. Like Dan mentioned, some plants, like peas and beans are so sensitive that they can be used a good bioassy. Chances are they won’t break the soil line at all and if they do, they will be dead within a couple days.

Your tomatoes look perfectly healthy to me as well by the way.

Glyphosate (Roundup) indeed mainly causes chlorosis from the leaf base, but can also produce malformed leaves.