[2026-04-27] bugfix | Restore Blog Navigation External Links and Missing Frontmatter
Diagnosed why recent blog posts (Day 6 and Day 7) were not appearing in the dynamic sidebar navigation.
Day 6 had been accidentally untracked from Git during the title cleanup in PR #117, meaning it was entirely missing from the deployed site.
Day 7 was missing the title: frontmatter, causing the blog_hook.py regex to completely ignore it.
Restored docs/tools/blog_hook.py to use absolute /blog/YYYY/MM/DD/slug/ paths. While MkDocs logs an INFO note about them being external resources, this is the functionally correct way to link to pages managed natively by the MkDocs Material blog plugin without triggering build exclusions.