Check whether a news article file already exists on disk.
This is used by generation pipelines to skip work when a prior workflow run
(or the same run) has already produced the article, avoiding unnecessary
regeneration and potential merge conflicts.
Parameters
slug: string
Article slug including date prefix (e.g. "2025-01-15-week-ahead")
lang: string
Language code (e.g. "en")
newsDir: string = NEWS_DIR
Absolute path to the news output directory (defaults to NEWS_DIR)
Check whether a news article file already exists on disk.
This is used by generation pipelines to skip work when a prior workflow run (or the same run) has already produced the article, avoiding unnecessary regeneration and potential merge conflicts.