feat: rich text editor, image crop component, empty DB resilience

- RichTextarea with toolbar (Bold, Italic, List, Heading) + Ctrl+B/I
  hotkeys (layout-independent), active state highlighting, preview mode
- Shared ImageCropField component (replaces duplicate in news/classes)
  with drag-to-reposition, Ctrl+scroll zoom, compact layout
- SectionEditor defaultData prop — all admin pages handle empty DB
- Team: section title editable, toast notifications, unsaved data warning
  on navigation (back button, sidebar links, browser close)
- Carousel: continuous card wrapping during drag, edge fade for small teams
- Markup renderer: **bold**, *italic*, ## headings, 🤍 bullet points
- Empty DB guards on all public site sections
- Fix: upload error handling, contact phone field, "team" section key

src/app/admin/_components/SectionEditor.tsx

@@ -7,6 +7,7 @@ import { adminFetch } from "@/lib/csrf";
 interface SectionEditorProps<T> {
   sectionKey: string;
   title: string;
+  defaultData?: Partial<T>;
   children: (data: T, update: (data: T) => void) => React.ReactNode;
 }
 
@@ -15,6 +16,7 @@ const DEBOUNCE_MS = 800;
 export function SectionEditor<T>({
   sectionKey,
   title,
+  defaultData,
   children,
 }: SectionEditorProps<T>) {
   const [data, setData] = useState<T | null>(null);
@@ -30,7 +32,7 @@ export function SectionEditor<T>({
         if (!r.ok) throw new Error("Failed to load");
         return r.json();
       })
-      .then(setData)
+      .then((loaded) => setData(defaultData ? { ...defaultData, ...loaded } as T : loaded))
       .catch(() => setError("Не удалось загрузить данные"))
       .finally(() => setLoading(false));
   }, [sectionKey]);