feat(builder): visual homepage blocks, merchant-language widget settings, real carousel arrows

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

P0 user feedback: homepage builder showed raw section.id like 'section-hero'/'section-categories'; hero widget exposed 'full-bleed'/'boxed' and raw px/vh as free text with no explanation; Overlay/Autoplay toggles made no sense without a slides concept; product carousel widgets rendered arrows nowhere near a working carousel.

Homepage section (sections list -> visual blocks):
- Replaced raw section.id display with a merchant-facing block catalog (icon + name + one-line explanation) for hero/categories/featured-products/product-carousel/recently-viewed/banner/partners/custom-html
- Added block catalog picker to append new blocks (was fixed at whatever the seed data had - task asked 'what if we add manually? not fixed 3')
- Added duplicate and remove per block, alongside the existing drag-to-reorder
- Verified in browser: labels render correctly, add-block and duplicate both confirmed working end-to-end

Widgets section (hero widget):
- 'Layout' free-text replaced with a select (Full width / Boxed) instead of typing 'full-bleed'/'boxed' blind
- 'Height' free-text replaced with a select (Compact/Medium/Tall/Full screen) mapped to real vh values
- New Slides editor: title/subtitle pairs an admin can add/remove: this is the actual multi-slide data the Overlay/Autoplay toggles were referring to with nothing to point at before
- HeroWidgetData contract gains slides[]/autoplay; HeroWidgetComponent now renders a real rotator (dots, click-to-jump, autoplay interval) when more than one slide exists - previously autoplay/overlay props existed but there was no slideshow behavior anywhere to control

Carousel arrows root cause and fix:
- widget-manifest.json offers 'carousel' as a layout option for product-collection/product-carousel widgets, and the admin UI let you select it, but ProductCarouselWidgetComponent always rendered a static CSS grid regardless - there was no carousel implementation to have arrows in the first place
- Now renders a real horizontally-scrollable strip with working prev/next buttons (native scrollBy, disabled at each end) when section.layout.strategy === 'carousel'; falls back to the existing grid otherwise
- Confirmed src/app/components/items-carousel (a PrimeNG p-carousel) is dead code, not wired into any route or widget - not the source of the reported bug

New builder.* i18n keys (en/ru/hy), zero duplicate-key collisions verified via scan

src/app/features/project-editor/sections/homepage-section.component.scss

@@ -0,0 +1,98 @@
+.block-list { display: grid; gap: 10px; margin: 10px 0; }
+
+.block-card {
+  display: grid;
+  grid-template-columns: auto auto 1fr auto;
+  gap: 12px;
+  align-items: start;
+  padding: 12px;
+  border: 1px solid var(--border-color, #d3dad9);
+  border-radius: var(--radius-sm);
+  background: #fff;
+
+  &.block-card--hidden { opacity: 0.6; }
+  &.cdk-drag-preview { box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15); }
+  &.cdk-drag-placeholder { opacity: 0.3; }
+}
+
+.block-card__handle {
+  cursor: grab;
+  color: var(--text-secondary, #6b7280);
+  padding-top: 4px;
+}
+
+.block-card__preview {
+  width: 44px;
+  height: 44px;
+  border-radius: var(--radius-sm);
+  background: var(--bg-secondary, #f7f8f8);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-size: 1.2rem;
+  color: var(--color-primary, #2f8f5b);
+}
+
+.block-card__title-row { display: flex; align-items: center; gap: 8px; }
+.block-card__desc { margin: 2px 0 8px; color: var(--text-secondary, #6b7280); font-size: 0.85rem; }
+
+.block-card__hidden-badge {
+  font-size: 0.7rem;
+  text-transform: uppercase;
+  letter-spacing: 0.4px;
+  color: var(--text-secondary, #6b7280);
+  border: 1px solid var(--border-color, #d3dad9);
+  border-radius: 999px;
+  padding: 1px 8px;
+}
+
+.block-card__actions {
+  display: flex;
+  flex-direction: column;
+  align-items: flex-end;
+  gap: 8px;
+
+  button {
+    border: none;
+    background: transparent;
+    cursor: pointer;
+    color: var(--text-secondary, #6b7280);
+
+    &:hover { color: var(--text-primary, #1e3c38); }
+  }
+}
+
+.block-card__visible-toggle { display: flex; align-items: center; gap: 6px; font-size: 0.8rem; }
+.block-card__remove:hover { color: var(--danger-color, #c0392b); }
+
+.block-catalog { margin-top: 16px; padding-top: 16px; border-top: 1px solid var(--border-color, #d3dad9); }
+
+.block-catalog__grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
+  gap: 8px;
+}
+
+.block-catalog__item {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 6px;
+  padding: 12px 8px;
+  border: 1px dashed var(--border-color, #d3dad9);
+  border-radius: var(--radius-sm);
+  background: var(--bg-secondary, #f7f8f8);
+  cursor: pointer;
+  font-size: 0.8rem;
+  color: var(--text-primary, #1e3c38);
+
+  .pi { font-size: 1.2rem; color: var(--color-primary, #2f8f5b); }
+
+  &:hover { border-color: var(--color-primary, #2f8f5b); background: #fff; }
+  &:focus-visible { outline: 2px solid var(--color-primary, #2f8f5b); outline-offset: 2px; }
+}
+
+@media (max-width: 640px) {
+  .block-card { grid-template-columns: auto 1fr; }
+  .block-card__actions { grid-column: 1 / -1; flex-direction: row; justify-content: flex-end; }
+}