Breaking changes:
- ForceGraphView customizes nodes with .nodeLabel, .nodeColor and .nodeRadius
  modifiers instead of initializer closures; the trailing closure is now the
  tap handler. ForceGraphStyle.labelSpacing is renamed minimumLabelSpacing.

Added:
- Warm start (ForceLayout.initialPositions, warmStartTemperature), used by
  ForceGraphView when nodes or edges change.
- ForceLayout.Simulation / makeSimulation() for stepping a layout manually.
- Hashable ForceLayout and ForceGraphStyle; memberwise initializers for
  ForceLayoutConfiguration and ForceGraphStyle; degrees and uniqueEdges
  properties; Codable GraphEdge; "Fit to view" accessibility action.
- tvOS 16 and watchOS 9 platforms for the layout.
- DocC landing page, doc comments, Scripts/check.sh.

Fixed:
- Edges linked in both directions are drawn once.
- README samples and install instructions.