feat: allow searching for people

[viniciuskloppel]

This change allows the search function to handle searches for "People" by using parse_users when kv["product"] == "People", while retaining the default behavior for tweets.

[viniciuskloppel]

Hey @vladkens, just to give you some context, I noticed that the search function could be extended to also search for people on X, since it's just another tab (or another kv["product"] in our case). This change makes the return type of the search function look like this: Generator[Tweet | User, Any, None].

Let me know if you think that's reasonable, or if you'd prefer to create a separate function for that (e.g., search_people).