fix(rag): prefer requested UC folder over stale subject mapping

Reapply "fix(rag): clear all cache key variants during ingestion to prevent stale index queries"

Revert "fix(rag): clear all cache key variants during ingestion to prevent stale index queries"

fix(rag): clear all cache key variants during ingestion to prevent stale index queries

refactor: remove redis for hf spaces compatibility

chore: initial deploy to HF Spaces