Revise default_mode to Literal (enum) and add to settings.yaml

private_gpt/settings/settings.py

@@ -350,7 +350,7 @@ class AzureOpenAISettings(BaseModel):
 class UISettings(BaseModel):
     enabled: bool
     path: str
-    default_mode: str = Field(
+    default_mode: Literal["RAG", "Search", "Basic", "Summarize"] = Field(
         "RAG",
         description="The default mode.",
     )

settings.yaml

@@ -25,6 +25,8 @@ data:
 ui:
   enabled: true
   path: /
+  # "RAG", "Search", "Basic", or "Summarize"
+  default_mode: "Summarize"
   default_chat_system_prompt: >
     You are a helpful, respectful and honest assistant.
     Always answer as helpfully as possible and follow ALL given instructions.