Add a Goldmark heading render hook that renders each Markdown heading with
its auto-generated id plus a hover-revealed anchor link, so any article
section can be linked to and shared. IDs still come from .Anchor, so
existing in-page `#section` links keep working, and author `{.class}`
attributes (e.g. .wp-block-heading) are preserved.

- themes/.../_markup/render-heading.html — the render hook
- themes/.../static/css/heading-anchors.css — hover styling + scroll-margin
  to clear the sticky header; loaded async alongside the other theme CSS
- single.html — the in-article smooth-scroll handler now also updates the
  URL hash, so clicking a section link makes it copyable from the address bar

fa-link is already in the icon subset, so generated assets are unchanged.

Closes #52

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Add a User Groups section off the community page where local PowerShell
user groups get their own page, plus a listing that shows all groups.

- New /user-groups/ section with list + single layouts (logo support,
  meeting details sidebar, multiple organizers)
- "User Groups" card added to the community menu (also appears in the
  Community nav dropdown)
- Self-service submission: user-group.yml issue form + add-user-group.yml
  workflow that generates the content file and opens a PR on approval
  (mirrors the community-event flow)
- Seed groups: PowerShell Ohio User Group (real details + logo from their
  Meetup) and Research Triangle PowerShell User Group
- Ohio's upcoming meeting added to the community calendar
- Regenerated purged Tailwind CSS and Font Awesome icon subsets

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

- List Stephen Valdinger as the Ohio PowerShell User Group organizer
- Regenerate assets/css/tailwind.css: earlier commit purged it before the
  content was final, dropping classes that only render once the calendar has
  an upcoming event (space-y-5, md:w-36, hover:border-purple-400, ...) and a
  group has a logo (max-w-full, max-h-full, p-1). Rebuilt with the pinned
  hugo-extended so the CI freshness check passes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>