chore: 将后端移动到 api/ 目录，准备合并为单仓库

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

api/utils/upload.py

@@ -0,0 +1,29 @@
+from ninja import Router, File
+from ninja.files import UploadedFile
+from pathlib import Path
+from django.conf import settings
+import uuid
+from account.decorators import super_required
+
+router = Router()
+
+
+@router.post("")
+@super_required
+def upload_to_media(request, image: File[UploadedFile]):
+    # 生成唯一的文件名
+    ext = Path(image.name).suffix
+    filename = f"{uuid.uuid4()}{ext}"
+
+    # 确保 media 目录存在
+    media_root = Path(settings.MEDIA_ROOT)
+    media_root.mkdir(exist_ok=True)
+
+    # 保存文件
+    file_path = media_root / filename
+    with open(file_path, "wb+") as f:
+        for chunk in image.chunks():
+            f.write(chunk)
+
+    # 返回文件URL
+    return {"url": f"{settings.MEDIA_URL}{filename}"}