fix: remove fallback content, fix video upload and positioning

- Remove hardcoded fallback data — DB is sole content source
- Sections render conditionally when data exists
- Hero video slots save after each upload (not only when all 3 filled)
- Video positions preserved (left/center/right) with empty string slots
- Client-side 10MB hard limit on video uploads with clear error
- Server-side upload error handling for body size limits
- Guard Team section against empty members array
- Clean up old uploaded images and videos

src/app/api/admin/upload/route.ts

@@ -10,10 +10,19 @@ const IMAGE_FOLDERS = ["team", "master-classes", "news", "classes"];
 const VIDEO_FOLDERS = ["hero"];
 const ALL_FOLDERS = [...IMAGE_FOLDERS, ...VIDEO_FOLDERS];
 const IMAGE_MAX_SIZE = 5 * 1024 * 1024; // 5MB
-const VIDEO_MAX_SIZE = 50 * 1024 * 1024; // 50MB
+const VIDEO_MAX_SIZE = 10 * 1024 * 1024; // 10MB
 
 export async function POST(request: NextRequest) {
-  const formData = await request.formData();
+  let formData: FormData;
+  try {
+    formData = await request.formData();
+  } catch (e) {
+    const msg = e instanceof Error ? e.message : "Upload failed";
+    return NextResponse.json(
+      { error: msg.includes("size") || msg.includes("multipart") ? "Файл слишком большой (макс. 10 МБ)" : `Ошибка загрузки: ${msg}` },
+      { status: 413 }
+    );
+  }
   const file = formData.get("file") as File | null;
   const rawFolder = (formData.get("folder") as string) || "team";
   const folder = ALL_FOLDERS.includes(rawFolder) ? rawFolder : "team";
@@ -26,16 +35,16 @@ export async function POST(request: NextRequest) {
   const allowedTypes = isVideoFolder ? VIDEO_TYPES : IMAGE_TYPES;
   if (!allowedTypes.includes(file.type)) {
     const msg = isVideoFolder
-      ? "Only MP4 and WebM videos are allowed"
-      : "Only JPEG, PNG, WebP, and AVIF are allowed";
+      ? "Допустимы только MP4 и WebM"
+      : "Допустимы только JPEG, PNG, WebP и AVIF";
     return NextResponse.json({ error: msg }, { status: 400 });
   }
 
   const maxSize = isVideoFolder ? VIDEO_MAX_SIZE : IMAGE_MAX_SIZE;
   if (file.size > maxSize) {
-    const label = isVideoFolder ? "50MB" : "5MB";
+    const label = isVideoFolder ? "10 МБ" : "5 МБ";
     return NextResponse.json(
-      { error: `File too large (max ${label})` },
+      { error: `Файл слишком большой (макс. ${label})` },
       { status: 400 }
     );
   }
@@ -45,7 +54,7 @@ export async function POST(request: NextRequest) {
   const allowedExts = isVideoFolder ? VIDEO_EXTENSIONS : IMAGE_EXTENSIONS;
   if (!allowedExts.includes(ext)) {
     return NextResponse.json(
-      { error: "Invalid file extension" },
+      { error: "Недопустимое расширение файла" },
       { status: 400 }
     );
   }