Fix Orphaned affiliateProducts Frontmatter

CONCLUSIONS:

• Articles with affiliateProducts: [] but containing /go/ links have inconsistent frontmatter.
• These articles require updating affiliateProducts to include the actual product IDs from the links for accurate affiliate tracking.

SUPPORTING DETAIL:

1. Audit Scope: Scan all fieldgrade articles for affiliateProducts: [] and search body content for /go/ links.
2. Mapping Logic: Extract product IDs from /go/ URLs (e.g., /go/12345 → 12345) and populate affiliateProducts array.
3. Validation: Ensure updated affiliateProducts matches all inline links in the article body.
4. Edge Cases: If an article has no /go/ links, retain affiliateProducts: [] to avoid false positives.