Detect SERP features (featured snippet, PAA, image pack, video, knowledge panel, AIO, local pack, sitelinks) that competitors capture for the site's tracked keywords but the site doesn't, and generate per-gap content-restructuring recommendations. Runs as a monthly cron (10th of month) via `scripts/serp-feature-tracker.mjs`, or interactively via `/serp-features {site}`. Output: `_inbox/serp-feature-gaps-{site}-{date}.md` with gaps grouped by recommended action (most map to `/refresh` with feature-specific flags). Use when the user types `/serp-features` or when the monthly cron fires.
