mallory — multiple expressions, one graph

Unlike the linked-panes view, which shares a CellGraph but still renders each pane on its own separate canvas. v1 supports plotting, free-variable sliders, and an f' overlay (dashed, same color) per row; point-dragging, exact mode, the step-by-step differentiation trace, area/region shading, and finite-structure scatter stay single-expression-only for now (see GraphCanvas). Root crossings (where a curve meets y=0) are marked automatically, via a declarative "condition" cell decoupled from the drawing decision — the Open MCT-inspired pattern the roadmap flagged for flagging points of interest generally, since generalized (same underlyingfindConditionCrossings) to an arbitrary threshold, not just y=0. Discontinuities (a singularity or domain boundary in a curve) are marked the same way too, as open circles. Pairwise intersections between every currently visible pair of curves are marked the same way, in purple. The full state (every row, its color/visibility/sliders, annotations, and the viewport) lives in the URL, so reload restores the session, and "Fork this view" is just opening that same URL in a new tab to explore an alternate path independently. "+ Annotate" then click the canvas drops a labeled note at that point — click a marker or its label to select it, drag a selected marker to move it, edit its label in the list, or "Jump" to recenter the viewport on it (drag the canvas to pan, scroll to zoom, at any time) — an Open-MCT-inspired point annotation with cross-pane-style navigation, here within one shared view. Append ?embed=1 to this URL (or use it directly as an <iframe> src) for a chrome-free embeddable view. Each row's "strict" toggle uses @johnhenry/math's Symbolic.assertVariables: once on, anything besides x is a hard error instead of silently becoming a new slider — useful for catching a typo before it turns into a spurious parameter.