Implement deadline matching logic for dashboard repository and enhance unit tests

- Added the `deadlineWithinWindowMatch` function to match raw deadline fields stored as Unix seconds or milliseconds, ensuring accurate filtering in MongoDB queries.
- Updated the `ClosingSoon` method in the repository to utilize the new deadline matching logic, improving query accuracy for upcoming deadlines.
- Introduced a new unit test, `TestDeadlineWithinWindowMatchCoversSecondsAndMilliseconds`, to validate the functionality of the deadline matching logic, ensuring both seconds and milliseconds are correctly handled.
- Enhanced comments in the `widget_cache` and `search_list_cache` files for better clarity on cache behavior and staleness.

This update improves the accuracy of deadline handling in the dashboard service and strengthens the test coverage for related functionalities.

internal/dashboard/service.go

@@ -427,6 +427,16 @@ func (s *service) warmWidgetCaches() {
 		}
 		return &ClosingSoonResponse{Items: items}, nil
 	})
+	go s.recentCache.Reload(strconv.Itoa(defaultListLimit), func(loadCtx context.Context) (*RecentResponse, error) {
+		items, nextCursor, err := s.repo.Recent(loadCtx, defaultListLimit, "")
+		if err != nil {
+			return nil, err
+		}
+		return &RecentResponse{
+			Items:      items,
+			NextCursor: nextCursor,
+		}, nil
+	})
 }
 
 func (s *service) loadTrend(ctx context.Context, query TrendQuery) (*TrendResponse, error) {