feat: clean up filters

Some sorely needed reorganization and pruning

config/filters/feed.js

@@ -0,0 +1,31 @@
+import { JSDOM } from "jsdom";
+
+// From coryd.dev
+// https://www.coryd.dev/posts/2025/generating-absolute-urls-in-my-rss-feeds/
+const convertRelativeLinks = (htmlContent, url) => {
+  if (!htmlContent || !url) return htmlContent;
+
+  const dom = new JSDOM(htmlContent);
+  const document = dom.window.document;
+
+  document.querySelectorAll("a[href]").forEach((link) => {
+    let href = link.getAttribute("href");
+
+    if (href.startsWith("#")) {
+      link.remove();
+      return;
+    }
+
+    if (!href.startsWith("http://") && !href.startsWith("https://"))
+      link.setAttribute(
+        "href",
+        `${url.replace(/\/$/, "")}/${href.replace(/^\/+/, "")}`,
+      );
+  });
+
+  return document.body.innerHTML;
+};
+
+export default {
+  convertRelativeLinks,
+};