Add article versioning support via doc_version taxonomy

[Copilot]

Implements multi-version documentation support to maintain separate docs for different software releases, similar to Symfony and ReadTheDocs.

Implementation

Taxonomy System

• New doc_version hierarchical taxonomy registered with REST API support
• Added to docs post type taxonomies array

Version Selection UI

• Dropdown selector in main content area (after breadcrumbs) and sidebar
• Visibility conditional: only renders when ≥2 versions exist
• URL-based version switching via ?version={slug} parameter
• Responsive CSS with mobile breakpoint

Helper Functions (includes/functions.php)

wedocs_get_versions()              // Retrieve all versions
wedocs_get_doc_version($post_id)   // Get versions for specific doc
wedocs_get_current_version($post_id) // Get active version (respects URL param)
wedocs_version_selector($post_id)  // Render dropdown UI

Frontend Behavior

// Version switcher updates URL with version parameter
$('.wedocs-version-dropdown').on('change', function() {
  const versionSlug = $(this).find('option:selected').data('slug');
  window.location.href = new URL(baseUrl).searchParams.set('version', versionSlug);
});

Files Changed

• includes/Post_Types.php - taxonomy registration
• includes/functions.php - version utilities (123 lines)
• templates/single-docs.php - main content selector
• templates/docs-sidebar.php - sidebar selector
• assets/build/frontend.css - dropdown styling (51 lines)
• assets/js/frontend.js - switching logic (25 lines)
• Version bumped to 2.1.19

Usage

Admins assign versions via taxonomy UI. Users see version dropdown on docs with multiple versions. Selection persists via URL parameter for bookmarking/sharing.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Feature request: Add support for multiple versions of the same article</issue_title>
<issue_description>Hi @tareq1988 !

Me again. I would like to ask you to consider adding another feature I think it would put your plugin in the next level: article versioning. When documenting, you have to update existing articles to adapt them to new features or new UI layouts, for instance, from you latest software version. But that doesn't mean previous information isn't correct for older versions of your software. That's why I think this is a great feature for you to add to your plugin.

Some examples would be:

Symfony's Documenation

Readthedocs.com [Check out lower left corner]

Thanks!</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Feature request: Add support for multiple versions of the same article #78

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