Move ~460 lines of imperative Canvas plot rendering (draw helpers, value/time axes, zoom state, context flyout, wheel handler, color theming, and the PlotBounds/PlotAxisLayout/PlotSeriesSample records) out of MainWindow into a new Controls/PlotView : Grid that owns its own Canvas. PlotWindow now hosts a PlotView instead of a raw Canvas; the shared rendering path collapses to PlotView.Redraw().
MainWindow shrinks from 2014 to 1445 lines; the inline plot pane and the windowed plot now share a single code path. Public API on PlotView: Redraw(), Clear(), ResetZoom(), ApplyTheme(AppThemeMode).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
JMR-devandCopilot