feat(contact): add support for customer contacts

[bclerc]

Change summary

Adds support for the customer contacts API under /customer/{customer_id}/contacts.

Three new client methods:

• Client.ListContacts
• Client.CreateContact
• Client.DeleteContact

The endpoint uses JSON:API with the customer_contact resource type. The Fastly API does not expose an update endpoint for contacts, so only list/create/delete are implemented.

The integration test creates a guard contact first because the API refuses to delete the last contact of a given type (You cannot remove the last <type> contact).

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New Feature Submissions:

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User Impact

Users can now manage customer-level contacts (primary, billing, technical, security, emergency) through the Go client instead of having to call the API directly. This unblocks support for customer contacts in the Terraform provider.

Are there any considerations that need to be addressed for release?

No breaking changes. New surface only.

[kpfleming]

Thanks for the PR! Unfortunately we are no longer adding API endpoints to the top-level fastly package unless they belong there because there are existing endpoints for the same resource type. Since this is a new resource type, it will need to be put into fastly/customer/contacts - refer to fastly/apisecurity/operations for an example of how this is done.

[bclerc]

Thanks for the quick review and for pointing me to the right pattern! I'll move the new endpoints into a dedicated fastly/customer/contacts sub-package and use fastly/apisecurity/operations as the reference. I'll push the refactor shortly.

[bclerc]

Done — I've pushed the refactor. The contacts client now lives at fastly/customer/contacts following the fastly/apisecurity/operations layout (Create/List/Delete with (ctx, *fastly.Client, *Input) signatures, pointer-valued inputs, fixtures moved under the sub-package). The endpoint is JSON:API so the code imports github.com/google/jsonapi directly for MediaType and the unmarshaling helpers — happy to adjust if you'd prefer a different approach there. CHANGELOG entry updated to feat(customer/contacts).

[kpfleming]

Thanks - we're about to start a three day weekend, so we'll look into this next week.