Add knowledge retrieval configuration to Assistant model and related components

- Introduce new fields for knowledge retrieval configuration in AssistantConfig and Assistant models, including mode, top_n, and score_threshold.
- Implement KnowledgeRetrievalConfig schema with validation for top_n.
- Update backend services and routes to handle knowledge retrieval settings.
- Enhance frontend components to support knowledge retrieval configuration, including a new dialog for advanced settings.
- Add tests for knowledge retrieval configuration validation and description generation.

backend/routes/assistants.py

@@ -151,6 +151,7 @@ async def _to_out(session: AsyncSession, assistant: Assistant) -> AssistantOut:
         vision_model_resource_id=assistant.vision_model_resource_id,
         model_resource_ids=await _resource_ids(session, assistant.id),
         knowledge_base_id=assistant.knowledge_base_id,
+        knowledge_retrieval_config=assistant.knowledge_retrieval_config or {},
         tool_ids=await _tool_ids(session, assistant.id),
         prompt=assistant.prompt,
         api_url=assistant.api_url,
@@ -217,6 +218,7 @@ async def duplicate_assistant(
         vision_enabled=source.vision_enabled,
         vision_model_resource_id=source.vision_model_resource_id,
         knowledge_base_id=source.knowledge_base_id,
+        knowledge_retrieval_config=dict(source.knowledge_retrieval_config or {}),
         prompt=source.prompt,
         api_url=source.api_url,
         api_key=source.api_key,