fix: use rawMarkdownBody filter instead of template.frontMatter.content

Eleventy 3.x no longer allows synchronous access to template internals
from pagination templates. Replace article.template.frontMatter.content
with a custom filter that reads the source file via gray-matter.

article-markdown.njk

@@ -12,7 +12,7 @@
   eleventyExcludeFromCollections: true
 }
 ---
-{%- set bodyContent = article.template.frontMatter.content -%}
+{%- set bodyContent = article.inputPath | rawMarkdownBody -%}
 {%- set tokens = (bodyContent.length / 4) | round(0, "ceil") -%}
 ---
 title: "{{ article.data.title | replace('"', '\\"') }}"

eleventy.config.js

@@ -456,6 +456,17 @@ export default function (eleventyConfig) {
     }
   });
 
+  // Extract raw Markdown body from a source file (strips front matter)
+  eleventyConfig.addFilter("rawMarkdownBody", (inputPath) => {
+    try {
+      const src = readFileSync(inputPath, "utf-8");
+      const { content } = matter(src);
+      return content.trim();
+    } catch {
+      return "";
+    }
+  });
+
   // Current timestamp filter (for client-side JS buildtime)
   eleventyConfig.addFilter("timestamp", () => Date.now());