dragbox: sync ax._input.range during pan and scroll-zoom

[robertcollar-kobold]

Summary

scaleZoom and Plotly.relayout both maintain the invariant that ax.range and ax._input.range stay in sync. Several mutation sites in dragbox.js violate it, only writing ax.range:

• zoomWheelOneAxis (mousewheel zoom)
• dz (corner-handle zoom on drag)
• updateMatchedAxRange (linked-axis update during drag)
• dragAxList (pan)

ax._input.range is what gd.layout.<axis>.range references. Leaving it stale means user code reading gd.layout.<axis>.range from a plotly_relayouting handler sees the previous range while gd._fullLayout already reflects the in-progress gesture. Anything that handler does (recomputing positions, fetching tiles, updating annotations) is computed against an out-of-date viewport, and only catches up once dragTail runs the eventual full relayout.

The fix is the minimal extension of the existing assignments to also write ax._input.range, matching the pattern already used by scaleZoom and the relayout path in plot_api.js.

How the bug manifests

Concrete repro: a tile-pyramid demo using a plotly_relayouting handler that reads gd.layout.xaxis.range to decide which OSM tiles to fetch on each frame of a wheel-zoom gesture. Across a tile-pyramid level boundary the handler computed tiles for the old range, so when the new tiles loaded they were rendered at coordinates that didn't match the actual viewport — geographic features visibly jumped.

A minimal in-page check before/after:

plotDiv.on('plotly_relayouting', function() {
  console.log({
    layout:     plotDiv.layout.xaxis.range.slice(),
    fullLayout: plotDiv._fullLayout.xaxis.range.slice()
  });
});
// fire a wheel event...

Before the fix: layout reports [0.4, 0.6], fullLayout reports [0.4095, 0.5905].
After the fix: both report [0.4095, 0.5905].

Test plan

• npm run test-jasmine -- cartesian_interact --nowatch --Chrome
• npm run test-jasmine -- axes --nowatch --Chrome
• Manual: open a chart with a plotly_relayouting handler logging both gd.layout and gd._fullLayout ranges; pan and wheel-zoom and verify they agree