feat(website): add source type badges for non-GitHub entries

Detect the hosting source (stdlib, GitLab, Bitbucket, External) from
the entry URL and surface it as a small badge in the stars column where
a star count would otherwise show an em dash.

Stdlib entries also get their own sort tier — between starred entries
and other no-star entries — so the standard library is not buried at
the bottom of each category.

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

website/templates/index.html

@@ -98,6 +98,7 @@
         </td>
         <td class="col-stars">
           {% if entry.stars is not none %}{{ "{:,}".format(entry.stars) }}{%
+          elif entry.source_type %}<span class="source-badge">{{ entry.source_type }}</span>{%
           else %}&mdash;{% endif %}
         </td>
         <td