feat(quote): enhance QuoteBlock and QuoteCarouselBlock components

- Updated QuoteBlock to support a new "center" variant for text alignment.
- Modified QuoteCarouselBlock to include an option for displaying navigation arrows.
- Enhanced type definitions for quote-related data structures to accommodate new features.
- Improved styling and layout handling for better visual presentation of quotes.

src/app.css

@@ -443,9 +443,9 @@ main pre code,
 }
 
 /* Zitate: Lora (Design System – nur für Zitate) */
-[data-block-type="quote"] blockquote,
-[data-block-type="quote"] blockquote p,
-[data-block-type="quote"] blockquote cite {
+blockquote[data-block-type="quote"],
+blockquote[data-block-type="quote"] p,
+blockquote[data-block-type="quote"] cite {
   font-family: var(--font-secondary);
 }