Every codegen-emitted Request / Result record now ships with a
sibling 0-arg fn that returns the record with every field set to
option.None. Callers spread it via Gleam's record-update syntax
to set just the fields they care about — turns the 20+ line
'pass None to every field' boilerplate into 3-4 lines:

  // Before:
  s3.GetObjectRequest(
    bucket: Some("b"), key: Some("k"),
    checksum_mode: None, expected_bucket_owner: None,
    if_match: None, /* ... 18 more None lines ... */
  )

  // After:
  s3.GetObjectRequest(
    ..s3.get_object_request_default(),
    bucket: Some("b"), key: Some("k"),
  )

Wired across all four protocol emitters (awsjson, restjson,
restxml, awsquery) including nested-struct sites. Pure addition
on top of v1.0; existing call sites that build the full record
keep compiling.

Examples migrate to the factory shape after v1.1.0 publishes
(they pin to hex; 1.0.0 doesn't have the factory yet).