EdgeLabelPosition = number | AbsoluteEdgeLabelPosition

Type representing edge label position — either relative (0-1) or absolute ('Npx').

• Relative (number, 0-1): percentage along the path. Clamped to [0, 1].
• Absolute (string, 'Npx'): pixel distance from source (positive) or target (negative). Clamped to path length.