User Experience: Fix `optimize_kl` minisanity plotting for runs with many parameters

Currently, the reduced-Chi² plots produced by optimize_kl become unreadable when reconstructing a model with many parameter keys or when doing many MGVI/GeoVI iterations.

This patch relocates the minisanity plot legend to outside of the graph area and resizes the figure adaptively to make it readable in both named scenarios. Adaptive resizing is also added to the energy history plot.

@mtr: Are you the right maintainer to ask to merge this? Has somebody been assigned to take over @parras position as maintainer?

Cheers, Lukas

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