Add S3 MinIO upload feature for lesson cover images in admin manager

src/components/AdminContentManager.tsx

@@ -102,6 +102,38 @@ export default function AdminContentManager({ token }: AdminContentManagerProps)
     }
   };
 
+  const [uploadingLessonImage, setUploadingLessonImage] = useState(false);
+
+  const handleLessonImageUpload = async (e: React.ChangeEvent<HTMLInputElement>) => {
+    const file = e.target.files?.[0];
+    if (!file) return;
+
+    const formData = new FormData();
+    formData.append('file', file);
+
+    setUploadingLessonImage(true);
+    try {
+      const res = await fetch('/api/admin/upload', {
+        method: 'POST',
+        headers: {
+          'Authorization': `Bearer ${token}`
+        },
+        body: formData
+      });
+      const data = await res.json();
+      if (res.ok && data.url) {
+        setLessonForm(prev => ({ ...prev, thumbnailUrl: data.url }));
+      } else {
+        alert(data.error || 'Erro ao fazer upload da imagem');
+      }
+    } catch (err) {
+      console.error(err);
+      alert('Erro de conexão ao fazer upload');
+    } finally {
+      setUploadingLessonImage(false);
+    }
+  };
+
   useEffect(() => {
     fetchCourses();
   }, []);
@@ -708,13 +740,25 @@ export default function AdminContentManager({ token }: AdminContentManagerProps)
 
                 <div className="md:col-span-3 space-y-2">
                   <label className="text-xs text-zinc-400 font-bold uppercase">Imagem de Capa da Aula (Thumbnail URL - Opcional)</label>
+                  <div className="flex items-center space-x-2">
                     <input
                       type="text"
                       value={lessonForm.thumbnailUrl}
                       onChange={(e) => setLessonForm({ ...lessonForm, thumbnailUrl: e.target.value })}
-                    placeholder="Cole a URL da imagem de capa para esta aula (ex: https://meuservidor.com/capa.jpg)"
-                    className="w-full glass-input rounded-lg p-3 text-xs text-white focus:outline-none"
+                      placeholder="Cole a URL ou use o botão para fazer upload para o S3"
+                      className="flex-1 glass-input rounded-lg p-3 text-xs text-white focus:outline-none"
                     />
+                    <label className="bg-zinc-800 hover:bg-zinc-700 text-white text-[11px] font-bold py-3.5 px-3 rounded-lg border border-white/10 transition-all flex items-center justify-center space-x-1.5 cursor-pointer select-none">
+                      {uploadingLessonImage ? 'Enviando...' : 'Upload S3'}
+                      <input
+                        type="file"
+                        accept="image/*"
+                        onChange={handleLessonImageUpload}
+                        disabled={uploadingLessonImage}
+                        className="hidden"
+                      />
+                    </label>
+                  </div>
                 </div>
 
                 <div className="md:col-span-3 space-y-2">