Update API specifications with fern api update

[github-actions]

Update API specifications by running fern api update.

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Note

Low Risk
OpenAPI-only contract updates; clients may need to handle breakpoints and reject empty parentId strings if they previously allowed them.

Overview
Syncs openapi.json with the latest Fern API definitions.

Diagram connections now expose an optional breakpoints array (up to 100 {x, y} points) on DiagramConnection, DiagramConnectionPartial, and DiagramConnectionRequired. The spec documents that breakpoints apply only to square line shapes and must form a valid orthogonal path.

Model object create/update schemas tighten parentId: when it is a string (non-null), it must have minLength: 1, so empty-string parents are invalid while null for the root remains allowed.

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