Unified Axis and Label Alignment

2.x uses a shared X-positioning pipeline across:

• chart rendering (LineChart, BarChart)
• axis labels (AxisLabels)

This removes drift where labels and marks used different spacing logic.

Domain behavior

Categorical data

chartData([Double])

• interpreted as category slots
• points are centered in slots
• labels map to slot-centered anchors

Numeric data

chartData([(Double, Double)])

• interpreted as continuous numeric domain
• points map by numeric x-values and optional chartXRange

Label APIs

.chartXAxisLabels(["M", "T", "W", "T", "F", "S", "S"])
.chartXAxisLabels([(0, "A"), (1, "B"), (2, "C")], range: 0...2)

Auto ticks

.chartXAxisAutoTicks(6, format: .number)
.chartYAxisAutoTicks(5, format: .number)
.chartXAxisLabelRotation(.degrees(-20))

Mixed bar + line guidance

For aligned mixed charts:

1. use the same data domain semantics for both layers
2. keep explicit chartXRange consistent when using numeric tuples
3. apply axis labels in the same container (AxisLabels) that wraps both layers