Copilot/update file selection drag drop

[tmaier-kettering]

This pull request adds drag-and-drop file selection support to the application's file input widgets, improving usability for users working with data files. The implementation uses the tkinterdnd2 library when available, and provides a reusable utility for enabling drag-and-drop on various widgets. The changes are grouped into core functionality, integration across modules, and user interface improvements.

Core drag-and-drop functionality:

• Added a new utility module ui/drag_drop.py that provides the enable_file_drop function for enabling drag-and-drop file selection on tkinter widgets, with support for file type filtering and robust parsing of dropped file paths.

Integration with main application and data import:

• Updated main.py to create the root window using TkinterDnD.Tk() when available, enabling drag-and-drop support throughout the application. [1] [2]
• Modified file_handling/data_import.py to support drag-and-drop file selection in the file dialog entry widget, including extension filtering based on allowed file types. [1] [2] [3]

Integration with additional modules:

• Enabled drag-and-drop file selection in the sampler UI (live_processing/sampler.py) and the two-page wizard (ui/two_page_wizard.py), allowing users to drop files directly onto the relevant widgets for immediate loading and preview. [1] [2] [3] [4]

User interface improvements:

• Updated instructional text in the wizard's file selection label to inform users that drag-and-drop is available.

These changes collectively enhance the user experience by making file selection faster and more intuitive, especially for workflows involving frequent data imports.