Enable saving and loading of navigation paths

Description

Allow users to save navigation paths they have created through connected nodes and load them later for reference or sharing.

Current Behavior

Navigation paths (if implemented) are temporary and lost when the page is refreshed or closed.

Desired Behavior (MoSCoW Prioritization)

Must Have

• Save Path: Users can save their current navigation path with a custom name or description
• Load Path: Users can load previously saved paths from a list or menu

Should Have

• Path Management: Users can view, rename, and delete saved paths
• Storage Options: Store paths in localStorage

Could Have

• Path Sharing: Paths can be shared via URL or exported for others to import
• File Export: Export paths as downloadable files
• Persistence: Saved paths persist across browser sessions

Depends On

This feature depends on the navigation path creation feature (#2) being implemented first.

Out of Scope

We don't need to handle what happens to stored paths if problem names are changed - paths may break and that's acceptable for this implementation.

Expected Outcome

Users can create, save, and revisit meaningful navigation paths through the problem network, enabling better analysis and knowledge sharing.