Update webhook schema to 2026-07-07.

[mattvagni]

Regenerate the webhook schema and update test fixtures for the new version.

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Note

Medium Risk
Minor semver bump but stricter version matching and broader accepted payload shapes can break consumers still on 2026-05-06 or code that assumed notes/users/tenants only matched the old schema.

Overview
Bumps @team-plain/webhooks to webhook target version 2026-07-07 (changeset minor), updating webhook-schema.json, generated webhook-schema.ts, fixtures, and signature hashes in verify-plain-webhook.test.ts.

Payload / type changes in this version: webhookMetadata.webhookTargetVersion is now fixed to 2026-07-07. componentUser.user may be a machineUser as well as a user. threadStatusDetail adds WAITING_INDEFINITELY. Tenant source adds attio and email_domain. Note / note-created text and markdown no longer require minLength: 1 (empty strings allowed, still capped at 10k).

Integrators on older webhook targets must align SDK and Plain webhook version or validation will reject mismatched payloads.

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