fix(cli): omit optional OpenAPI request bodies

[robinbraemer]

Defect

Commands generated from an OpenAPI operation with requestBody.required: false still send a JSON null payload when their input omits body. That changes an absent body into a present invalid value.

The production dogfood command akua order-drafts create-worker-bootstrap --input - with only { "path": { "id": "..." } } received 422 Invalid input: expected object, received null, although the public contract marks its JSON body optional.

Reproduction

A local intercepted-transport run of the current CLI executor with the analogous optional-body machines.update operation and input { "path": { "id": "mch_capture" }, "headers": { "if-match": "0" } } captured:

PATCH https://api.akua.dev/v1/machines/mch_capture
Content-Type: application/json
body: null

No request reached production during this reproduction.

origin/main retains the same generated shape for orderDrafts.createWorkerBootstrap:

• openapi/public.json declares requestBody.required: false.
• src/generated/public-operation-executor.gen.ts maps omitted input.body to payload: undefined but still passes the payload field.
• src/generated/openapi-api.gen.ts represents the request as [RequestJson, HttpApiSchema.NoContent].
• Effect HttpApiClient then encodes the NoContent branch using its default JSON payload encoding, yielding null.

No existing akua-dev/cli issue matched optional bodies, null payloads, or NoContent.

Acceptance criteria

• Omitting body for every optional JSON request body sends no request bytes and no Content-Type header.
• Supplying body: {} or an allowed populated object still sends the JSON object and validates it strictly.
• Explicit body: null remains a client-side input validation error.
• A generated-command regression test covers orderDrafts.createWorkerBootstrap (including its colon-suffixed path) and one ordinary optional-body operation.
• Required request bodies continue to fail before transport when omitted.

Scope

Fix the generic OpenAPI/Effect client generation or request serialization boundary; do not add a handwritten exception for worker bootstrap.