Folder Import Improved

When importing a folder that contains subfolders, choose from three modes:

1. Single Category (flat): Import all items into one category.
2. Single Category with Tags: Import all items into one category; each item is tagged with its subfolder name.
3. (Pro) Category Directory: Create a parent category for the top folder and child categories for each subfolder.
   • Parent includes link buttons to child categories; children include a link back to the parent.
   • Child categories are hidden from the category grid by default (visible in Edit mode).

Categories & Navigation

• Category Link Button: Jump directly to a target category with one click.
• Show/Hide Hidden Categories: New toggle in the category grid (in Edit mode only).
• Back/Forward Navigation: Return to previously selected categories with Back and Forward buttons (keyboard and midi bindings possible)
• Bulk Delete: Delete multiple selected categories at once.

Fixes

• Long-press & Right-click: Resolved an issue where a long-press (right-click) could erroneously trigger a left-click afterward.
• Playlist Deletions: Playlist items now delete correctly.