Support relative result return from claim search

We could use some way to return bottom half, or top 10-20% of items from a result of claim search. This could allow us to do something like a "up and coming category" - where instead of showing the top results from claim search, we'd show the ones 10% down and lower. This would allow discovery of new content that hasn't quite made it into the top of trending to give it more attention. We could also do this by first calling claim search and then figuring out what params to pass, but it would be easier with just a 1 shot call.

Start by locating the claim search API and documenting how its current result parameters and ordering work. Define the expected meaning of relative ranges such as the bottom half or top 10–20% down, then verify that a single claim-search call returns the requested slice for discovery use cases.