feat: add repository pattern, service layer architecture, and scheduler management

- Implement repository pattern for data access layer
- Add comprehensive service layer for business logic
- Create scheduler management system with health monitoring
- Add bounded buffer utility for memory management
- Enhance security audit logging with retention policies

lib/types.ts

@@ -70,6 +70,7 @@ export interface ChatSession {
   summary?: string | null; // Brief summary of the conversation
   messages?: Message[]; // Parsed messages from transcript
   transcriptContent?: string | null; // Full transcript content
+  questions?: string[]; // Extracted questions from the conversation
 }
 
 export interface SessionQuery {