refactor: unify plotting on Plotly; Plot saves (png) and shows intera…

[alirezabayatmk]

Summary 📝

Every Murano plot is now interactive Plotly, and Plot is a single generic step that saves and displays whichever plottable results are present. The steps/probing/ subpackage and ProbePlot are gone; probing is one branch of Plot.

Details

1. Plot dispatches over steering, probe, logit-lens, and logit-attribution results. It saves each figure under plots/ and displays it inline when run in a notebook. Attention and SAE plots stay as direct murano.plotting calls (they need an explicit head/feature).
2. Ported the steering and probe plots from matplotlib/seaborn to Plotly, so the whole visualization layer is interactive. matplotlib and seaborn are dropped from the [plot] extra; _common.py is removed.
3. Saved format is user-selectable via Plot(save_format=...), default png. [plot] pins kaleido<1 so PNG export works on headless Slurm/CI out of the box; it falls back to self-contained interactive HTML if static export is ever unavailable.

Checks

• Tested Changes