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.toHtml.test.ts

@@ -73,3 +73,65 @@ describe('Section.toHtml shape divider color/height XSS hardening', () => {
     expect(html).not.toContain('<svg');
   });
 });
+
+describe('Section.toHtml vertical alignment (justify-content + min-height)', () => {
+  test('is always a column flex container (display:flex;flex-direction:column)', () => {
+    const { html } = toHtml({}, 'child');
+    expect(html).toContain('display:flex');
+    expect(html).toContain('flex-direction:column');
+  });
+
+  test('style.justifyContent flows into the emitted style attribute', () => {
+    const { html } = toHtml({ style: { justifyContent: 'center' } }, 'child');
+    expect(html).toContain('justify-content:center');
+  });
+
+  test('style.minHeight flows into the emitted style attribute', () => {
+    const { html } = toHtml({ style: { minHeight: '600px' } }, 'child');
+    expect(html).toContain('min-height:600px');
+  });
+});
+
+describe('Section.toHtml box-model styles (margin/padding/border/shadow/opacity)', () => {
+  test('margin/padding/border/box-shadow/opacity all flow into the emitted style attribute', () => {
+    const { html } = toHtml(
+      {
+        style: {
+          marginTop: '10px', marginRight: '10px', marginBottom: '10px', marginLeft: '10px',
+          paddingTop: '5px',
+          border: '2px solid #ff0000',
+          boxShadow: '0 4px 8px rgba(0,0,0,0.12)',
+          opacity: '0.8',
+        },
+      },
+      'child',
+    );
+    expect(html).toContain('margin-top:10px');
+    expect(html).toContain('padding-top:5px');
+    expect(html).toContain('border:2px solid #ff0000');
+    expect(html).toContain('box-shadow:0 4px 8px rgba(0,0,0,0.12)');
+    expect(html).toContain('opacity:0.8');
+  });
+});
+
+describe('Section.craft.props exposes the vertical-alignment/box-model/animation/visibility rollout', () => {
+  test('animation, animationDelay, hideOnDesktop/Tablet/Mobile are present with blank/false defaults', () => {
+    const props = (Section as any).craft.props;
+    expect(props.animation).toBe('');
+    expect(props.animationDelay).toBe('0');
+    expect(props.hideOnDesktop).toBe(false);
+    expect(props.hideOnTablet).toBe(false);
+    expect(props.hideOnMobile).toBe(false);
+  });
+
+  test('style carries blank/default vertical-alignment and box-model keys', () => {
+    const style = (Section as any).craft.props.style;
+    expect(style).toHaveProperty('justifyContent');
+    expect(style).toHaveProperty('minHeight');
+    expect(style).toHaveProperty('marginTop');
+    expect(style).toHaveProperty('paddingTop');
+    expect(style.border).toBe('none');
+    expect(style.boxShadow).toBe('none');
+    expect(style.opacity).toBe('1');
+  });
+});