fix(packages): render Markdown on provider View Details

[Ibochkarev]

What changed and why

Extras on modx.com ship Markdown in description, instructions, and changelog. On Package Manager → View Details those fields still arrived as raw text, so Omise showed [Omise](…) links and ## Setup headings instead of formatted HTML.

I added PackageMarkdown (Parsedown with safeMode) and run it in Workspace/Packages/Rest/GetList for provider list/details payloads. Local GetAttribute reuses the same helper for transport attributes. Provider license stays plain text for the Information aside. CSS for code / pre / img now also applies under #modx-package-browser-details-main.

How to test

1. Manager → Extras → Installer → Download Extras (modx.com).
2. Search Omise, open View Details.
3. Description should show a real link to omise.co, not [Omise](https://www.omise.co).
4. Instructions should show headings (Setup, Customising the Payment Form) and a styled code block.
5. Aside License should still read as a short plain string (e.g. GPLv2), not wrapped in <p>.
6. Install flow: open Readme / Changelog / License tabs on a local package and confirm Markdown still renders.

php -l core/src/Revolution/Transport/PackageMarkdown.php
php -l core/src/Revolution/Processors/Workspace/Packages/GetAttribute.php
php -l core/src/Revolution/Processors/Workspace/Packages/Rest/GetList.php
# exit 0

core/vendor/bin/phpcs --standard=phpcs.xml \
  core/src/Revolution/Transport/PackageMarkdown.php \
  core/src/Revolution/Processors/Workspace/Packages/GetAttribute.php \
  core/src/Revolution/Processors/Workspace/Packages/Rest/GetList.php \
  _build/test/Tests/Model/Transport/PackageMarkdownTest.php
# exit 0

core/vendor/bin/phpunit -c _build/test/phpunit.xml --filter PackageMarkdownTest
# exit 0 (4 tests, 12 assertions)

Related issue(s)/PR(s)

Resolves #15329

Related: Markdown for local package attributes landed in #13853 / #16829; this extends the same idea to provider View Details.

Compatibility notes

Manager Package Management + modx.com (or other) providers. PHP 8.1+. Uses existing erusev/parsedown dependency. Compiled default theme CSS updated from _package-management.scss.

Breaking change assessment

Workspace/Packages/Rest/GetList now returns HTML for description, instructions, and changelog instead of raw Markdown/plain text. The manager Ext templates already inject those fields as HTML. Short license strings are unchanged. Safe for a patch if only the manager consumes this connector.

Test coverage

_build/test/Tests/Model/Transport/PackageMarkdownTest.php — links/headings, field filtering, provider fields leave license plain, safeMode strips raw <script>.

Contributors

@muzzwood reported the original need (Omise-style Markdown from the extras form).

AI tool use

Cursor (Composer) drafted PackageMarkdown, the processor wiring, tests, and this PR body. I checked Omise’s live provider payload (description / instructions Markdown) and ran the Gate E commands above before opening the PR.