Allow Analytics to display a single origin/destination path

### Who would benefit from this feature? _No response_ ### What is this feature about? The [refactoring of the Analytics feature](https://github.com/OpenRailAssociation/netzgrafik-editor-frontend/pull/903) is impressive and made one of our user to suggest to be able to: 1. Enable Analytics 2. Click on a node (the "origin"): now, we can see all the shortest paths taken to all the other nodes 3. Click on another node (the "destination"): now, we see only the shortest path from the origin node to the destination node <img width="1790" height="504" alt="Image" src="https://github.com/user-attachments/assets/3df61d54-00df-40c9-bd68-83170e98b442" /> It would have been pleasant to be able to click first on Aarau, then on Brugg. ### Why is this feature valuable? This would help to navigate in big networks, especially when some trains are not stopping at nodes that they use for the shortest path, it is difficult to differentiate them of the other shortest paths.