Release 1.3.0

Added

• Webhooks: add WebhookTargetType and SUPPORTED_WEBHOOK_EVENT_TYPES_BY_TARGET to document and validate target/event compatibility.
• Webhooks: add typed models for subscriptions (WebhookSubscription) and ensure results (EnsureWebhookSubscriptionResult).
• Webhooks: add idempotent setup helpers:
  • WebhookClient.ensure_subscription() (create/update/noop + optional dry_run)
  • WebhookClient.ensure_default_subscriptions() (derive PROFILE/USER targets from account and subscribe to all valid events)

Changed

• Minimum supported Python version is now 3.9 (Python 3.8 is no longer supported).

Fixed

• CI: format/sort imports to satisfy black/isort checks.
• Release workflow: fix GitHub release creation and attach a zipped dist/ artifact.