Topology-aware loss function for combined pixel-wise and topology loss

Nobody has claimed this yet.

At the moment we are using pixel-wise loss functions for our segmentation models. These loss functions are great for overall segmentation problems but they fail to capture topology inherent in our satellite imagery.

One example use-case is roads. The pixel-wise loss functions don't penalize for connectivity issues.

We should look into topological-aware loss functions to help with these problems and to directly optimize for example for connectivity instead of having to do a much more difficult task in post-processing.

Idea:
- look into https://arxiv.org/abs/1712.02190 https://arxiv.org/abs/1603.08155
- try out a combined loss `a * pixelwise + b * topology`

No files, tests, or entry points are named. Start by reading the two linked papers, then inspect how the repository currently defines and applies pixel-wise segmentation losses. Done means evaluating a topology-aware loss combined as `a * pixelwise + b * topology` for improved connectivity.

Written by the indexing model from the issue text.