feat(builder): nav/menu link-to-page picker, page sync, download attr, box-model rollout

NavStylePanel (Navbar/Menu/Logo/Footer):
- LinkPicker: dropdown of the site's pages (read-only via usePages()) plus
  manual URL / #anchor / tel: / mailto: entry, wired into every link-href
  field (standalone Logo href, Navbar logoUrl, Navbar/Menu link items).
- "Sync links with Pages" button in the Links section: repopulates the
  links array from the current pages list (label = page name, href = '/'
  for the landing page else '/{slug}'), preserving any existing CTA link.
  Regression-fix vs the legacy GrapesJS builder, which had this.
- `download` checkbox per link (Navbar/Menu links, standalone Logo href)
  emits the `download` attribute on export for links to files.
- Links/Colors sections now gate on the component actually carrying a
  `links`/color prop, so Footer (no links array) no longer shows a dead
  "Add Link" editor.
- Box-model (Margin/Padding via SpacingControl, Border & Effects via
  BorderControl + box-shadow presets + opacity), AnimationControl, and
  VisibilityControl added for all four owned components, backed by new
  animation/animationDelay/hideOnDesktop/hideOnTablet/hideOnMobile props
  (with blank/default values in each component's .craft.props).

Tests: NavStylePanel.test.tsx (new, 17 tests: LinkPicker modes, sync
preserves CTA, download toggle, box-model/animation/visibility wiring) +
extended Navbar/Menu/Logo/Footer .toHtml.test.ts (download attribute,
craft.props defaults). Full suite: 683/683 passing. `npm run build` green.

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

craft/src/components/basic/Navbar.tsx

@@ -11,6 +11,8 @@ interface NavLink {
   href: string;
   isExternal?: boolean;
   isCta?: boolean;
+  /** Adds the `download` attribute to the exported anchor (F3: links to files). */
+  download?: boolean;
 }
 
 interface NavbarProps {
@@ -33,6 +35,11 @@ interface NavbarProps {
   isSticky?: boolean;
   showMobileMenu?: boolean;
   style?: CSSProperties;
+  hideOnDesktop?: boolean;
+  hideOnTablet?: boolean;
+  hideOnMobile?: boolean;
+  animation?: string;
+  animationDelay?: string;
 }
 
 /* ---------- Defaults ---------- */
@@ -149,6 +156,7 @@ export const Navbar: UserComponent<NavbarProps> = ({
             href={link.href}
             target={link.isExternal ? '_blank' : undefined}
             rel={link.isExternal ? 'noopener noreferrer' : undefined}
+            download={link.download || undefined}
             onClick={(e) => e.preventDefault()}
             onMouseEnter={() => setHoveredLink(i)}
             onMouseLeave={() => setHoveredLink(null)}
@@ -200,6 +208,11 @@ Navbar.craft = {
     style: {
       borderBottom: '1px solid #e4e4e7',
     },
+    hideOnDesktop: false,
+    hideOnTablet: false,
+    hideOnMobile: false,
+    animation: 'none',
+    animationDelay: '0',
   } as NavbarProps,
   rules: {
     canDrag: () => true,
@@ -308,6 +321,7 @@ Navbar.craft = {
   // Add CSS class to each link for hover
   const linksHtmlWithClass = links.map((link) => {
     const target = link.isExternal ? ' target="_blank" rel="noopener noreferrer"' : '';
+    const downloadAttr = link.download ? ' download' : '';
     const cls = link.isCta ? 'navbar-cta' : 'navbar-link';
     const linkStyle = cssPropsToString({
       textDecoration: 'none',
@@ -319,7 +333,7 @@ Navbar.craft = {
       borderRadius: link.isCta ? '6px' : '0',
       transition: 'color 0.15s, background-color 0.15s',
     });
-    return `<a href="${escapeAttr(safeUrl(link.href || "#"))}" class="${cls}"${target}${linkStyle ? ` style="${linkStyle}"` : ''}>${escapeHtml(link.text)}</a>`;
+    return `<a href="${escapeAttr(safeUrl(link.href || "#"))}" class="${cls}"${target}${downloadAttr}${linkStyle ? ` style="${linkStyle}"` : ''}>${escapeHtml(link.text)}</a>`;
   }).join('\n      ');
 
   return {