docs: add repository, enabled, required frontmatter to all plugin docs

Added repository, enabled, and required fields to the frontmatter of
all 44 plugin documentation files. Updated Plugins.base to include
these columns, matching the information previously in the manual tables.
Also filtered out internal plugins (Assets, Static, ComponentResources,
NotFoundPage) from the base query.

docs/plugins/ArticleTitle.md

@@ -3,6 +3,9 @@ title: ArticleTitle
 tags:
   - plugin/component
 image:
+repository: "quartz-community/article-title"
+enabled: true
+required: false
 ---
 
 This plugin renders the article title from the page's frontmatter as an `<h1>` heading at the top of the page content. It reads the `title` field from frontmatter (falling back to the filename if no title is set).