feat(builder): containers package -- vertical alignment + box-model/anim/vis rollout

- ColumnLayout: exposes style.alignItems on its flex ROW (aligns uneven
  columns) -- render/toHtml already spread `style` onto the row div, so this
  is a craft.props default + panel control addition, no structural change.
- Container/Section: root element is now unconditionally display:flex;
  flex-direction:column (both editor render and toHtml), so the new
  Vertical Alignment control maps to style.justifyContent, paired with a
  Min Height (NumericUnitInput) control on style.minHeight. Default
  justify-content/align-items reproduce ordinary block-flow stacking, so
  this is a visual no-op for existing published content. Works in both
  normal and "boxed" (contentWidth) modes -- the boxed inner wrapper's own
  margin:0-auto horizontal centering is preserved via flex auto-margin
  override semantics.
- ContainerStylePanel (serves Container/Section/Columns) distinguishes the
  Columns case from Container/Section via nodeProps.columns/split presence
  (no typeName plumbing needed) to pick align-items vs justify-content for
  the shared Vertical Alignment control.
- All 3 owned components: added margin/padding (per-side)/border/box-shadow/
  opacity style defaults + AnimationControl/VisibilityControl-backed
  animation/animationDelay/hideOnDesktop/hideOnTablet/hideOnMobile props.
  New containerBoxModel.tsx (package-local, not shared.tsx) DRYs the
  box-model + border/effects + animation/visibility panel sections across
  the single shared ContainerStylePanel, mirroring the sibling media
  package's mediaBoxModel.tsx.
- Tests: extended all 3 *.toHtml.test.ts files (align-items/justify-content/
  min-height emission, box-model style emission, craft.props presence).
  673 tests green, tsc + vite build clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

craft/src/components/layout/Section.tsx

@@ -27,6 +27,11 @@ interface SectionProps {
   bottomDividerColor?: string;
   bottomDividerHeight?: string;
   anchorId?: string;
+  hideOnDesktop?: boolean;
+  hideOnTablet?: boolean;
+  hideOnMobile?: boolean;
+  animation?: string;
+  animationDelay?: string;
 }
 
 /* ---------- Divider renderer ---------- */
@@ -105,6 +110,14 @@ export const Section: UserComponent<SectionProps> = ({
       id={anchorId || undefined}
       style={{
         width: '100%',
+        // Section's root is always a column flex container so
+        // `style.justifyContent` (Vertical Alignment control, paired with
+        // `style.minHeight`) has an axis to act on -- see the matching note
+        // in Container.tsx for why this is a no-op for existing content
+        // (default justify-content/align-items reproduce ordinary block
+        // stacking).
+        display: 'flex',
+        flexDirection: 'column',
         position: (hasTopDivider || hasBottomDivider) ? 'relative' : undefined,
         ...style,
       }}
@@ -143,7 +156,17 @@ export const Section: UserComponent<SectionProps> = ({
 Section.craft = {
   displayName: 'Section',
   props: {
-    style: { padding: '40px 0', backgroundColor: '#ffffff' },
+    style: {
+      padding: '40px 0',
+      backgroundColor: '#ffffff',
+      minHeight: '',
+      justifyContent: '',
+      marginTop: '', marginRight: '', marginBottom: '', marginLeft: '',
+      paddingTop: '', paddingRight: '', paddingBottom: '', paddingLeft: '',
+      border: 'none',
+      boxShadow: 'none',
+      opacity: '1',
+    },
     innerMaxWidth: '1200px',
     topDivider: 'none',
     topDividerColor: '#ffffff',
@@ -152,6 +175,11 @@ Section.craft = {
     bottomDividerColor: '#ffffff',
     bottomDividerHeight: '50px',
     anchorId: '',
+    animation: '',
+    animationDelay: '0',
+    hideOnDesktop: false,
+    hideOnTablet: false,
+    hideOnMobile: false,
   },
   rules: {
     canDrag: () => true,
@@ -202,6 +230,8 @@ function buildDividerHtml(
 
   const outerStyle = cssPropsToString({
     width: '100%',
+    display: 'flex',
+    flexDirection: 'column',
     position: (hasTopDivider || hasBottomDivider) ? 'relative' : undefined,
     ...props.style,
   });