Update API specifications with fern api update

[github-actions]

Update API specifications by running fern api update.

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Note

Medium Risk
Webhook event type string changes are breaking for existing subscribers; new socket broadcast contracts may require client updates.

Overview
Regenerates openapi.json from Fern. The spec adds real-time diagram content over sockets (subscribe/unsubscribe client events and diagram-content-broadcast with diagramContent, id, and type), plus grouped SocketMessages / SocketMessageType entries.

Webhooks change in a breaking way: WebhookEventType values move from collection.operation dots to collection:operation colons (e.g. model-connection:created). New structured types WebhookEvent, WebhookEventCollection, and WebhookEventOperation describe payload shape.

Also adds DiagramContentNullable, shared DocumentBroadcastType / QueryBroadcastType enums (added, initial, modified, removed), and drops OpenAPI default: true on organization aiFeaturesEnabled and oauthLandscapeWriteEnabled across Partial/Required/Organization schemas.

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