[FEATURE]: Add dynamic sorting of the tooltip legend ordering for hovermode='x unified' mode

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Description

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Please add dynamic sorting of the tooltip legend ordering for hovermode='x unified' mode, so that when the user move the mouse over the chart, the legend showing up in the tooltip block reflects the ascending order of the legend value for that specific x value.

Why should this feature be added?

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This will drastically improve the intuitiveness of the tooltip block information, making direct comparison between different trace at a certain x value much more easier.

Mocks/Designs

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Notes

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No files, tests, or entry points are named. Start by locating the implementation of hovermode='x unified' and its tooltip legend ordering, then determine how values at each x position can be sorted dynamically. Done means the tooltip reflects ascending legend-value order for the hovered x value without changing other hover modes.