Add markdown-export plugin for serving posts/pages as markdown

[Copilot]

Adds a WordPress plugin that responds with markdown versions of posts and pages when the URL path ends with .md. Uses the existing MarkdownProducer component.

Changes

• New plugin: plugins/markdown-export/plugin.php
  • Hooks into template_redirect to intercept .md requests
  • Resolves post/page by path using get_page_by_path() with fallback to slug lookup
  • Converts content via MarkdownProducer with frontmatter (title, date, excerpt)
  • Returns 404 for missing posts
  • RFC 5987 compliant Content-Disposition header

Usage

GET /my-post.md          → Markdown of post with slug "my-post"
GET /parent/child.md     → Markdown of hierarchical page

Example Output

---
post_title: "Hello World"
post_date: "2025-01-15 10:00:00"
---

Welcome to my blog.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/PHPCSStandards/PHP_CodeSniffer/zipball/8da41e9a9fe4cc14d23cf7fcef3b80476f54e511
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/fyuDcm /usr/bin/composer install --quiet (http block)
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/aFcZoM /usr/bin/composer install (http block)
• https://api.github.com/repos/PHPCSStandards/composer-installer/zipball/e9cf5e4bbf7eeaf9ef5db34938942602838fc2b1
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/fyuDcm /usr/bin/composer install --quiet (http block)
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/aFcZoM /usr/bin/composer install (http block)
• https://api.github.com/repos/PHPCompatibility/PHPCompatibility/zipball/9fb324479acf6f39452e0655d2429cc0d3914243
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/fyuDcm /usr/bin/composer install --quiet (http block)
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/aFcZoM /usr/bin/composer install (http block)
• https://api.github.com/repos/doctrine/instantiator/zipball/0daa7cfba7b009aa3c95ae585322fb596a4ca2ae
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/fyuDcm /usr/bin/composer install --quiet (http block)
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/aFcZoM /usr/bin/composer install (http block)
• https://api.github.com/repos/myclabs/DeepCopy/zipball/07d290f0c47959fd5eed98c95ee5602db07e0b6a
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/aFcZoM /usr/bin/composer install (http block)
• https://api.github.com/repos/phar-io/manifest/zipball/65f90285728eae4eae313b8b6ba11b2f5436038e
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/aFcZoM /usr/bin/composer install (http block)
• https://api.github.com/repos/phar-io/version/zipball/4f7fd7836c6f332bb2933569e566a0d6c4cbed74
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/fyuDcm /usr/bin/composer install --quiet (http block)
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/aFcZoM /usr/bin/composer install (http block)
• https://api.github.com/repos/phpstan/phpstan/zipball/fcf8b71aeab4e1a1131d1783cef97b23a51b87a9
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/fyuDcm /usr/bin/composer install --quiet (http block)
  • Triggering command: /usr/bin/php8.3 /usr/bin/php8.3 -n -c /tmp/aFcZoM /usr/bin/composer install (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Build a simple WordPress plugin that adds the ability to respond with markdown version of my posts and pages if the requested path ends with .md. Assume php-toolkit.phar is available and leverage components/Markdown/class-markdownproducer.php

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