[Feature]: Enhance RAG with Document Summaries in System Prompt

## Feature Request
Add support for including individual document summaries in the system prompt when using multiple knowledge bases in RAG mode.

## Current Behavior
When working with multiple documents in RAG, the system prompt doesn't include document-level summaries, which could improve retrieval accuracy and context
understanding.

## Proposed Solution
Include a summary for each document in the system prompt when multiple knowledge bases are loaded. This would help the model better understand which document
contains which information.

## Benefits
- Improved retrieval precision
- Better context awareness
- Enhanced response relevance
- More efficient document utilization