security: OWASP audit and hardening (v1.0.8)

- Archive XSS: wrap get_the_archive_title/description with wp_kses_post()
  in ContextBuilder to sanitize Editor-editable term content rendered via |raw
- Comment fields: esc_html() on comment_author, esc_url() on comment_author_url
  at data source; template updated to output pre-escaped URL via |raw
- dark-mode.js: whitelist localStorage value against ['dark','light'] to
  prevent attribute injection from third-party script tampering
- TwigService: add is_safe=>html to esc_html/esc_attr/esc_url Twig functions
  to prevent double-encoding if autoescape is ever enabled
- Add .markdownlint.json (disable MD024 duplicate headings, MD013 line length)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,19 @@
 
 All notable changes to this project will be documented in this file.
 
+## [1.0.8] - 2026-02-19
+
+### Security
+
+- **Archive XSS hardening**: `ContextBuilder::getArchiveData()` now wraps `get_the_archive_title()` and `get_the_archive_description()` with `wp_kses_post()`. Term descriptions are user-editable by Editors and above; without sanitization an injected `<script>` tag would execute via the `|raw` filter in `archive.html.twig`
+- **Comment author XSS hardening**: `ContextBuilder::buildCommentTree()` now applies `esc_html()` to `comment_author` and `esc_url()` to `comment_author_url` at the data source, preventing injection via user-supplied comment fields
+- **Dark mode localStorage whitelist**: `getPreferredTheme()` in `dark-mode.js` now validates the stored theme value against `['dark', 'light']` before use, preventing attribute injection from a tampered localStorage value written by a third-party script
+- **Twig escaping functions marked safe**: `esc_html()`, `esc_attr()`, and `esc_url()` registered in `TwigService` are now declared with `['is_safe' => ['html']]`, preventing double-encoding if Twig autoescape is ever enabled
+
+### Changed
+
+- `views/partials/comment-item.html.twig`: Comment author URL now output via `{{ comment.author_url|raw }}` (escaped in PHP) instead of calling `esc_url()` from the template, keeping escaping logic in one place
+
 ## [1.0.7] - 2026-02-18
 
 ### Added