[Feature Request] Support folders in navigation bar for organizing task lists

[kodebarista]

Issue/Description:
Add support for hierarchical folders in the navigation bar so users can organize multiple task lists under logical groups. This enables better project structuring and reduces clutter when managing many lists.

Example structure:

Android Dev (folder)
├── App 1 (list)
│ ├── todo1
│ └── todo2
└── App 2 (list)

The navigation UI can follow a tree-view pattern similar to COSMIC Player, allowing expandable and collapsible folders.

Expected Behavior:
Users should be able to:

• Create folders
• Nest task lists inside folders
• Expand/collapse folders in the navigation panel
• Maintain clean hierarchy without flattening all lists

Other Notes:
Single nesting would be more than enough