13a09e2f2f
Remove the per-zone mutex that serialized all layer fills of the same zone. fillSingleZone() is read-only on zone state, so concurrent fills of different layers are safe. Make m_needRefill atomic and narrow the CacheTriangulation lock to the map lookup. Also add an R-tree index to reduce queries over large zones. Fixes https://gitlab.com/kicad/code/kicad/-/issues/23450