Document 404 job_not_found and 422 type_mismatch on bulk contacts (Preview)

[VarshSuresh]

Why?

The bulk contacts endpoints can return two error responses this spec did not document, so integrators had no way to know to handle them and would only discover them in production:

• a 404 / job_not_found when the request body's job.id names a job that does not exist
• a 422 / type_mismatch when contacts is not an array, or an element of it is not an object

Found while auditing the bulk companies error responses for parity with bulk contacts.

How?

Added the missing 404 response and two extra 422 examples to the three bulk contacts write endpoints, matching the codes and messages the API actually returns. The 404 sits between 401 and 422 to keep responses in numeric order.

Affects the Preview version only, where these endpoints are defined.

_{Generated with Claude Code}

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Update: added 403 / forbidden

A third undocumented error response, confirmed against a live response body: appending to a job that has already closed returns 403 with code forbidden and message job <job_id> is closed for new task updates.

Added to the same three write endpoints, ordered before 404. Each now documents 202, 401, 403, 404, 422.

The example uses the job_v2_1 placeholder that the other job examples in this spec already use, rather than a real job id.