Add typed JSON output to app webhook trigger - #8817

WHY are these changes introduced?

Let scripts read webhook delivery results. Related to #23671.

WHAT is this pull request doing?

Add --json with the topic, API version, delivery method, address, and delivery status. Remote delivery reports enqueued; localhost delivery reports delivered after a successful HTTP response. JSON request and local delivery failures use the shared error document. Preserve text output and mask signing secrets in request diagnostics.

Text: Webhook has been enqueued for delivery.
JSON: {"status":"success","delivery":{"topic":"orders/create","apiVersion":"2026-10","deliveryMethod":"http","address":"https://example.com/webhooks","status":"enqueued"}}.

How to manually test your changes?

Use a linked test app and a local webhook handler.

1. Run shopify app webhook trigger --topic orders/create --api-version <api-version> --address http://localhost:3000/webhooks --json > result.json. Check that the handler receives the sample and stdout has one result with delivery.status set to delivered.
2. Make the handler return HTTP 500 and repeat. Expect one error object and a nonzero exit. Repeat without --json to compare the existing warning.
3. Run shopify app webhook trigger --json-schema to inspect the delivery contract. Use an HTTPS address to check the remote enqueued result.

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• Added the required changesets