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/panels/right/styles/ContainerStylePanel.tsx

@@ -10,18 +10,40 @@ import {
   ColorSwatchGrid,
   GradientSwatchGrid,
   PresetButtonGrid,
+  NumericUnitInput,
   labelStyle,
   inputStyle,
   sectionGap,
   useNodeProp,
 } from './shared';
+import { BoxModelSection, BorderEffectsSection, AnimVisSection } from './containerBoxModel';
 
-/* ---------- CONTAINER / SECTION ---------- */
+// Vertical Alignment options shown to the user identically regardless of
+// which CSS property they end up mapped to (align-items for the Columns
+// flex ROW vs. justify-content for Container/Section's flex COLUMN root --
+// see the per-type branch below).
+const VERTICAL_ALIGN_OPTIONS: { label: string; value: string }[] = [
+  { label: 'Top', value: 'flex-start' },
+  { label: 'Center', value: 'center' },
+  { label: 'Bottom', value: 'flex-end' },
+  { label: 'Stretch', value: 'stretch' },
+];
+
+/* ---------- CONTAINER / SECTION / COLUMNS ---------- */
 export const ContainerStylePanel: React.FC<StylePanelProps> = ({ selectedId, nodeProps }) => {
   const style: CSSProperties = nodeProps.style || {};
 
   const { setProp, setPropStyle } = useNodeProp(selectedId);
 
+  // ColumnLayout only ever carries `columns`/`split` props -- Container and
+  // Section never set them -- so checking either alone distinguishes the
+  // flex-ROW case (align its columns via align-items, aligning uneven
+  // column heights) from the flex-COLUMN case (Container/Section, which
+  // vertically center/position their OWN content via justify-content,
+  // paired with a Min Height control so centering is meaningful).
+  const isColumns = nodeProps.columns !== undefined || nodeProps.split !== undefined;
+  const vAlignKey = isColumns ? 'alignItems' : 'justifyContent';
+
   return (
     <>
       {nodeProps.cssId !== undefined && (
@@ -94,6 +116,30 @@ export const ContainerStylePanel: React.FC<StylePanelProps> = ({ selectedId, nod
           ))}
         </div>
       </div>
+      <div className="guided-section">
+        <SectionLabel>Vertical Alignment</SectionLabel>
+        <PresetButtonGrid
+          presets={VERTICAL_ALIGN_OPTIONS}
+          activeValue={style[vAlignKey] as string}
+          onSelect={(v) => setPropStyle(vAlignKey, v)}
+        />
+      </div>
+      {!isColumns && (
+        <div className="guided-section">
+          <SectionLabel>Min Height</SectionLabel>
+          <NumericUnitInput
+            value={(style.minHeight as string) || ''}
+            onChange={(v) => setPropStyle('minHeight', v)}
+            units={['px', 'vh', '%']}
+            placeholder="auto"
+          />
+        </div>
+      )}
+
+      {/* Box model + border/effects + animation/visibility rollout */}
+      <BoxModelSection style={style} setPropStyle={setPropStyle} />
+      <BorderEffectsSection style={style} setPropStyle={setPropStyle} />
+      <AnimVisSection nodeProps={nodeProps} setProp={setProp} />
     </>
   );
 };