Add Lua filter for title string

posts/filters/title.lua

@@ -0,0 +1,15 @@
+-- source: https://stackoverflow.com/a/76048743
+
+local title
+
+function Header(e)
+  if title then return end
+  title = pandoc.utils.stringify(e) .. " • jutty.dev"
+end
+
+function Meta(e)
+  if not e.pagetitle then
+    e.pagetitle = title
+    return e
+  end
+end