fix: nahravanie velkych obrazkov - priamo do Supabase cez podpisanu URL, zmensenie na 2000 px

Vercel odmietal poziadavky nad 4,5 MB (Request Entity Too Large) a bucket
berie najviac 10 MB.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/components/editor/ImageUploadInput.tsx

@@ -2,6 +2,7 @@
 
 import React, { useRef, useState } from 'react';
 import { Upload, Loader2, Image as ImageIcon } from 'lucide-react';
+import { shrinkImage, uploadFile } from '@/lib/upload';
 
 interface ImageUploadInputProps {
   label?: string;
@@ -32,22 +33,10 @@ export const ImageUploadInput: React.FC<ImageUploadInputProps> = ({
 
     setIsUploading(true);
     try {
-      const formData = new FormData();
-      formData.append('file', file);
-
-      const res = await fetch('/api/upload', {
-        method: 'POST',
-        body: formData
-      });
-
-      const data = await res.json();
-      if (data.success && data.url) {
-        onChange(data.url);
-      } else {
-        alert(`Chyba pri nahrávaní obrázka: ${data.error || 'Neznáma chyba'}`);
-      }
+      const small = await shrinkImage(file);
+      onChange(await uploadFile(small, small.name));
     } catch (err: any) {
-      alert(`Chyba: ${err.message}`);
+      alert(`Chyba pri nahrávaní obrázka: ${err.message}`);
     } finally {
       setIsUploading(false);
       if (fileInputRef.current) {