Fabric navigation experience improvements

Currently, users access various workloads--such as Power BI, Data Engineering, Data Warehouse, and Data Science--through the button in the lower-left corner. While this approach was intended to provide flexibility, we've heard that it can be confusing, leaving users uncertain about when and why to switch between workloads.Now, we're refining how users open and interact with the product to simplify the workflow and make navigation more intuitive.