s3_exists_uri Function

    function s3_exists_uri(uri) result(exists)
        character(len=*), intent(in) :: uri
        logical :: exists
        character(len=:), allocatable :: bucket, key
        type(s3_config) :: temp_config
        logical :: uri_parsed

        exists = .false.

        ! Try to parse as s3:// URI
        call parse_s3_uri(uri, bucket, key, uri_parsed)
        if (.not. uri_parsed) then
            ! Not a s3:// URI, treat as regular key
            exists = s3_object_exists(uri)
            return
        end if

        ! Use parsed bucket if different from current config
        if (allocated(bucket) .and. len_trim(bucket) > 0) then
            temp_config = current_config
            temp_config%bucket = bucket
            call s3_init(temp_config)
            exists = s3_object_exists(key)
            ! Restore original config
            call s3_init(current_config)
        else
            exists = s3_object_exists(key)
        end if
    end function s3_exists_uri