Visualize turn restrictions: leftovers

- [ ] When detecting TRs from OSM upfront, filter them out if they're redundant with a one-way. If a user wants to change this, they shouldn't have to take two actions, and the one-way is "stronger" than a TR, since it covers all source roads.
- [ ] Construct a unit test for the above. Also add another unit test based on https://www.openstreetmap.org/relation/15006809, where there's both a oneway and TR, but the TR is not redundant.
- [ ] Consider de-emphasizing or hiding U-turns on dual carriageways. They're implied and probably easily understood by most users, so they just become noise.
- [ ] When hovering on a TR icon, try showing a two-line arrow or using some kind of red/black gradient to show the direction more clearly

The issue involves turn restrictions (TRs) and one-way street logic in a map visualization tool. Start by finding where TRs are detected from OSM data and where they are filtered or visualized. Look for existing unit tests related to turn restrictions to understand the codebase. The goal is to implement logic to filter redundant TRs, add unit tests, and improve the UI for displaying TR icons and U-turns on dual carriageways.

Written by the indexing model from the issue text.