UploadFile missing required file argument causes TypeError

UploadFile instantiation fails with TypeError if file argument is not provided. The file parameter became required in Starlette 0.24.0, breaking existing code that relied on automatic file creation.

Update all UploadFile instantiations to explicitly pass a file argument. Create SpooledTemporaryFile and pass to UploadFile constructor. Search codebase with `grep -r "UploadFile" .` to find all usages. Test all file upload endpoints after changes.