feat: RAG answers with sutta citations (M1)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/ask.py

@@ -0,0 +1,7 @@
+import sys
+from pathlib import Path
+from buddhagpt.rag import answer
+
+r = answer(sys.argv[1], "mlx-community/Qwen2.5-7B-Instruct-4bit", Path("data/lancedb"))
+print(r["answer"])
+print("\nSources:", ", ".join(c["uid"] for c in r["citations"]))