#2310 Every webhook lifecycle line is logged twice by swamp serve

Found while triaging swamp-club#2303; cosmetic and deliberately left out of that fix.

Summary

Each webhook lifecycle event produces two identical lines in serve output.

Cause

src/serve/webhook.ts logs directly at the completion, failure and abort sites, and then emits a WebhookEvent. src/cli/commands/serve.ts:3868-3910 handles that event and logs the same message a second time. Both run in log mode, so the tail carries duplicates.

Reproduction

Observed in a scratch repo on 20260918.211634.0-sha.bcaa9695. A single signed POST to a webhook route produced a received line, a queued line, a combined received-and-queued line, and the workflow failure line twice.

Expected

One line per lifecycle event. The event handler in serve.ts is the better single owner, since it already distinguishes log mode from json mode.