Humanise an article-type slug the same way humanizeStem does in
src/aggregator/analysis-aggregator.ts. Kept in sync by value — we
deliberately do not import the private helper.
Parameters
slug: string
Slug like week-ahead or breaking_news
Returns string
Title-cased humanised form (Week Ahead, Breaking News)
Humanise an
article-typeslug the same wayhumanizeStemdoes insrc/aggregator/analysis-aggregator.ts. Kept in sync by value — we deliberately do not import the private helper.