refactor: adopt markdown-to-jsx AST parser to simplify llms.txt output handling

Author: quantizor

package.json

@@ -21,7 +21,7 @@
     "fathom-client": "^3.7.2",
     "feed": "^5.1.0",
     "framer-motion": "^12.20.0",
-    "markdown-to-jsx": "9",
+    "markdown-to-jsx": "^9.4.1",
     "motion": "^12.20.0",
     "next": "15.3.4",
     "open-graph-scraper-lite": "^2.1.0",