Clarify "shared nodes" meaning

Perhaps with help text, or by renaming it to something more specific.

Suggestion: Rename to "only show genes with shared interactions" with help text "if toggled off, all genes in the result set will be shown with their interaction(s) regardless of whether they share an interaction with other genes in the result set, or have no interactions at all."

Start by locating the UI control labeled "shared nodes" in the JavaScript project; the issue names no file or test. Update the label or help text so the toggle's effect on genes with shared, individual, or no interactions is unambiguous, and verify the displayed wording matches the suggestion.

Written by the indexing model from the issue text.