Add confirmation dialogs and validation for site and folder deletions

[abhishekjnvk]

enhances the user experience of deleting nodes (sites and folders) in the session dialog by adding confirmation dialog. It also adjusts UI scaling defaults for macOS.

Improvements to node deletion safety and UX:

• Added a guard to prevent deletion of the root node in the session tree (NewSessionDlg.java).

• add confirmation dialogs when deleting nodes: a simple yes/no dialog for sites, and a folder-name entry dialog for folders to prevent accidental deletion. Supporting helper methods added for folder detection and confirmation (NewSessionDlg.java).

UI scaling improvements:

• Defaulted the UI scale factor to 1.0 for macOS to address Retina rendering issues, unless overridden by the user (ScalingUtil.java).