feat: show "Not on PyPI" badge for missing download counts

Replaces the em dash in the PyPI Downloads column with a source-badge
pill labeled "Not on PyPI", reusing the existing badge style used by
the stars column for visual consistency. Sorting is unaffected since
non-numeric cells already parse as missing.

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

website/templates/category.html

@@ -155,7 +155,10 @@
           </td>
           <td class="col-downloads">
             {% if entry.downloads is not none %}{{
-            "{:,}".format(entry.downloads) }}{% else %}&mdash;{% endif %}
+            "{:,}".format(entry.downloads) }}{% else %}<span
+              class="source-badge"
+              >Not on PyPI</span
+            >{% endif %}
           </td>
           <td class="col-stars">
             {% if entry.stars is not none %}{{ "{:,}".format(entry.stars) }}{%

website/templates/index.html

@@ -206,7 +206,10 @@
           </td>
           <td class="col-downloads">
             {% if entry.downloads is not none %}{{
-            "{:,}".format(entry.downloads) }}{% else %}&mdash;{% endif %}
+            "{:,}".format(entry.downloads) }}{% else %}<span
+              class="source-badge"
+              >Not on PyPI</span
+            >{% endif %}
           </td>
           <td class="col-stars">
             {% if entry.stars is not none %}{{ "{:,}".format(entry.stars) }}{%