v2: per-series scales and axis configuration (SeriesConfig.scale)

2.0.0-alpha.1 hardcodes a single y scale in StreamChartController.build() (src/StreamChartController.ts:336-342), SeriesConfig (:9-24) has no scale field, and axes is never configured — the only occurrence in src/ is a doc comment on StreamChart.tsx:113.

That means series with different units cannot share a chart. Concretely: plotting motor phase current (~2 A) alongside DC bus voltage (~24 V) on one autoscaled y flattens the current into the baseline. The workaround is a second chart, which then needs the two to stay aligned in time — see the geometry-alignment issue.

The uplot escape hatch doesn't quite get there: scales and axes merge/replace fine, but attaching series to custom scales means supplying the whole series array, and deepMerge treats arrays as scalars (isPlainObject is false for arrays, :477-487), so that replaces the generated stroke/width/paths/spanGaps mapping wholesale.

Related, and worth fixing regardless: structuralSignature JSON-stringifies config.uplot, so function-valued options (a custom range, tick formatters) drop out of the signature and changing them doesn't trigger a rebuild.

Suggested shape: scale?: string on SeriesConfig, passed through in build(), with uplot.scales / uplot.axes supplying the rest.

This was the primary blocker for a real streaming-scope consumer, which hand-rolled on raw uPlot instead.

Start in src/StreamChartController.ts:336-342 and inspect SeriesConfig at lines 9-24, then read deepMerge at lines 477-487 and structuralSignature. Implement the suggested per-series scale flow while preserving generated series mappings, and ensure function-valued uplot options can affect rebuilds; verify that custom scales and axes work without requiring a second chart.