Add RAG configuration options and enhance parameter configurability

- Add top-k and cosine-threshold parms for api server
- Update .env and cli parms handling with new parameters
- Improve splash screen display
- Update bash and storage classes to read new parameters from .env file.

lightrag/base.py

@@ -1,3 +1,4 @@
+import os
 from dataclasses import dataclass, field
 from typing import (
     TypedDict,
@@ -32,7 +33,7 @@ class QueryParam:
     response_type: str = "Multiple Paragraphs"
     stream: bool = False
     # Number of top-k items to retrieve; corresponds to entities in "local" mode and relationships in "global" mode.
-    top_k: int = 60
+    top_k: int = int(os.getenv("TOP_K", "60"))
     # Number of document chunks to retrieve.
     # top_n: int = 10
     # Number of tokens for the original chunks.