Edit turn restrictions: leftovers

- [ ] Check results near https://www.openstreetmap.org/way/158782224. The maptiler basemap seems wrong here; there's no oneway.
- [ ] Arrows too small at https://www.openstreetmap.org/node/5113845431
- [x] Depends on #101
- [ ] Decide what turn restrictions to visualize, especially when they clash with oneways

Test cases:
- a "blackhole" of oneways pointing at each other
- a simple example https://www.openstreetmap.org/relation/3880112

Followups from #180:

- [ ] Account for one-ways in get_turn_restriction_targets` (See [here](https://github.com/a-b-street/ltn/pull/180#discussion_r1976002464) -- maybe not -- maybe instead highlight redundant or conflicting cases)
- [ ] bug: Click on a road to make a TR from it, click map, blue focus remains
- [ ] bug: Click to delete a TR, preview line remains
- [ ] improve toolbar width responsiveness
- [ ] make pico tooltips on the toolbar buttons cover the map
- [ ] Maybe rotate the TR icon in the popup when showing what'll be created
- [ ] `turn_restrictions` could be a BTreeMap, and `travel_flows` ought to be a Vec