feat: widen node modal, two-column layout, unclip side handles

- NodeModal: widen to max-w-3xl; split into Information (left) and Design
  (right) columns with headers; Notes moved to left as a resizable textarea
- Connection Points: spatial cross of -/N/+ steppers around a node preview
  (replaces the four stacked sliders)
- BaseNode: drop overflow-hidden from the node root so left/right handles are
  no longer clipped to an ungrabbable sliver (inner sections keep their own
  clipping; rounded corners preserved)

ha-relevant: yes

frontend/src/components/canvas/nodes/BaseNode.tsx

@@ -56,7 +56,7 @@ export function BaseNode({ id, data, selected, icon: typeIcon, width, height }:
 
   return (
     <div
-      className="relative flex flex-col rounded-lg border transition-all duration-200 overflow-hidden"
+      className="relative flex flex-col rounded-lg border transition-all duration-200"
       style={{
         background: colors.background,
         borderColor: colors.border,