Function abort_multipart_upload 

pub async fn abort_multipart_upload(
    client: &Client,
    bucket: &BucketId,
    key: &str,
    upload_id: &str,
    source: MultipartSource,
    multipart_table: &MultipartTable,
    profile_id: &ProfileId,
    confirmed_unknown: bool,
) -> Result<(), AppError>

Abort a single in-progress multipart upload.

Safety guard

If source == Unknown and confirmed_unknown == false, the call is rejected with AppError::Validation { field: "confirmedUnknown", … }. This prevents accidental abortion of uploads started by other tools or sessions without explicit user acknowledgement.

Post-abort cleanup

On a successful abort of a Brows3r-sourced upload, the corresponding record is removed from multipart_table so the cleanup scanner no longer sees it.