feat(builder): implement visual homepage builder

New HomepageOverviewComponent (Tasks 1+8), mounted at the top of the
existing Homepage section page: completion ring, active/hidden section
counts, recommended next step, last-modified timestamp, and a 6-item
Homepage Health checklist (hero/categories/products/promotion/
newsletter/any-sections) - all derived from the real page.sections/
widgets data already in the facade, nothing fabricated.

Existing page-level drag-and-drop reordering (homepage-section's
CdkDragDrop over page.sections) was already implemented pre-Sprint 5 -
left as-is per "build on top of, do not replace."

Widgets section (Task 2) rewritten from a bare list into visual cards:
per-widget icon + humanized type label (hero/categories/product-
collection), a visible/hidden toggle and badge, up/down move buttons
(keyboard-accessible reorder within a section - see Known limitations
for why this replaces pointer drag for widgets specifically), duplicate,
and remove (with confirm). The existing per-type field editors (hero/
categories/product-collection) are unchanged; the raw-JSON fallback for
unknown widget types now sits behind a collapsed "Advanced settings"
disclosure instead of being the default view.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/i18n/en.ts

@@ -780,6 +780,28 @@ export const en: Translations = {
     brandSocialEmpty: "No social share image yet - shared links will show a blank card until you add one.",
     brandAccentColor: 'Accent',
     brandBorderColor: 'Borders',
+    homepageOverviewTitle: 'Homepage',
+    homepageOverviewSubtitle: "What your marketplace's homepage is made of.",
+    homepageOverviewComplete: 'Your homepage is fully set up.',
+    homepageActiveSections: 'Active sections',
+    homepageDisabledSections: 'Hidden sections',
+    homepageHealthHero: 'Hero banner added',
+    homepageHealthCategories: 'Featured categories added',
+    homepageHealthProducts: 'Featured products added',
+    homepageHealthPromotion: 'Promotion block added',
+    homepageHealthNewsletter: 'Newsletter signup added',
+    homepageHealthAnySections: 'The page has at least one section',
+    widgetTypeHero: 'Hero banner',
+    widgetTypeCategories: 'Featured categories',
+    widgetTypeProducts: 'Featured products',
+    widgetHidden: 'Hidden',
+    widgetVisible: 'Show',
+    widgetMoveUp: 'Move up',
+    widgetMoveDown: 'Move down',
+    widgetDuplicate: 'Duplicate',
+    widgetRemove: 'Remove',
+    widgetRemoveConfirm: 'Remove this section from the homepage?',
+    widgetAdvancedSettings: 'Advanced settings',
   },
   dashboard: {
     title: 'Dashboard',