Confirm and normalize J.J. / JJ Allaire spelling

The site uses two forms: JJ Allaire (people page title, most content) and J.J. Allaire (a handful of posts). These produce different Hugo slugs (jj-allaire vs j.j.-allaire), so J.J. Allaire entries don't link to the /people/jj-allaire/ page.

#166 normalized blog posts to JJ Allaire to match the current people page title, but the preferred form may actually be J.J. Allaire.

To do

1. Confirm which spelling is preferred
2. Update content/people/jj-allaire/_index.md title
3. Rename the directory to match the new slug (Hugo matches people values by slugifying them and comparing to the directory name)
4. Re-run sync-videos.py and update-software-frontmatter.py — they read the people page title, so they'll propagate the change automatically
5. Update blog posts (10 files)

Current state

First confirm the preferred spelling, then inspect content/people/jj-allaire/_index.md and the 10 affected blog posts. Read sync-videos.py and update-software-frontmatter.py before rerunning them, then verify the people directory slug and propagated references. Done means one consistent spelling, matching title and directory, and no stale links or front matter.