feat: start using bullmq to schedule pdf conversions

Author: tfhuhtal

package-lock.json

@@ -90,6 +90,7 @@
     "@tanstack/react-query": "^5.81.2",
     "@tanstack/react-query-devtools": "^5.81.2",
     "axios": "^1.6.8",
+    "bullmq": "^5.58.0",
     "chromadb": "^3.0.12",
     "cors": "^2.8.5",
     "date-fns": "^4.0.0",