Update MinIO bucket configuration and enhance dashboard service caching

- Changed the default MinIO bucket name from "opplens-documents" to "opplens" across multiple configuration files.
- Introduced caching for dashboard statistics in the service layer to improve performance and reduce redundant data fetching.
- Implemented a mutex for thread-safe access to cached statistics, ensuring data integrity during concurrent requests.

This update streamlines the configuration for the AI summarizer and optimizes the dashboard service, enhancing overall system efficiency.

internal/tender/repository.go

@@ -150,6 +150,13 @@ func NewRepository(mongoManager *orm.ConnectionManager, logger logger.Logger) Te
 			{Key: "tender_deadline", Value: 1},
 			{Key: "created_at", Value: 1},
 		}),
+		*orm.NewIndex("documents_scraped_at_idx", bson.D{
+			{Key: "processing_metadata.documents_scraped", Value: 1},
+			{Key: "processing_metadata.documents_scraped_at", Value: -1},
+		}),
+		*orm.NewIndex("scraped_documents_scraped_at_idx", bson.D{
+			{Key: "scraped_documents.scraped_at", Value: 1},
+		}),
 		// Index for CPV matching queries
 		*orm.NewIndex("cpv_matching_idx", bson.D{
 			{Key: "status", Value: 1},