fix(security): resolve chromadb pre-auth code injection CVEs by reverting to secure 0.6.3 pin

Author: kherrera6219

requirements.txt

@@ -56,7 +56,7 @@ aiohttp==3.14.0
 requests==2.34.2
 
 # RAG and orchestration stack
-chromadb==1.5.9
+chromadb==0.6.3
 llama-index==0.14.22
 sentence-transformers==5.5.1
 transformers>=5.0.0