[search] support pagination

Now that DA's API supports continuation tokens, search (queue / tree / traverse) should also support this.

## Critiera of acceptance
1. Searching for content respects continuation tokens.
2. Traversing content respects continuation tokens.

Start by locating the search implementations for queue, tree, and traverse, then review how the DA API exposes continuation tokens. Verify the behavior with the repository's existing checks or search-related tests. Done means content searches and traversals both respect continuation tokens.

Written by the indexing model from the issue text.