Fix packages table

[stertooy]

Fixes #381. Though, I'm not sure this is an optimal solution.

The problem with the current table is that first a 5-columns-wide is created (was changed in d437882 to provide a non-JavaScript version of the table). The DataTables script, however, has 6 columns defined, and this doesn't mix well. This causes the missing cell in the table footer... and other things, like the missing "Subtitle" header.

The simplest fix of all would be to just insert the missing column between Date and Subtitle again. But then the non-javascript version of the table has an empty column to the left, and an empty column between Date and Subtitle.

What this PR does instead is created two copies of the table: one with 4 columns intended for non-JS, and one with 6 columns intended for JS. The second one is hidden by default, but once the page is loaded and JavaScript is available, it hides the first table and makes the second one visible.

[fingolfin]

Thank. One thing I missed during code review, but now put into a commit: the "version" in the URL for loading the JavaScript should be updated to ensure visitors get the new JavaScript even when they recently visited the page and everything is cached. I.e.:

commit 61664da67fe3c94e96dbb94281e3b3c3a4fc8757
Author: Max Horn <[email protected]>
Date:   2025-10-18 12:11:57 +0200

    Force reloading JavaScript

diff --git a/packages/index.md b/packages/index.md
index 238db712..322dfdaa 100644
--- a/packages/index.md
+++ b/packages/index.md
@@ -9,7 +9,7 @@ permalink: /packages/
 <!-- load datatables -->
 <script src="{{ site.baseurl }}/assets/js/datatables.min.js?version=1"></script>
 
-<script type="module" src="{{ site.baseurl }}/assets/js/loadPackageTable.js?version=4"></script>
+<script type="module" src="{{ site.baseurl }}/assets/js/loadPackageTable.js?version=5"></script>
 
 <!-- List of deposited packages -->
 There are {{ site.data.package-infos | size }} packages that are shipped with GAP {{site.data.release.version}}.