feat: plan mode for wasserförderung

### Problem / use case

As an operator I want to plan the water pipeline on a map.

Give start and endpoint - program chooses path and calculates total length as well as the location of pumps

### Proposed solution

see above

### Alternatives considered

_No response_

### Context

- [x] I am using (or intend to use) Lagebuch operationally in a fire brigade