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 sync from Fern; no application code in the diff, though clients and validators may start enforcing the new fields and parentId constraint.

Overview
Regenerates openapi.json via Fern to match the current API surface.

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, with orthogonal routing constraints (shared x/y between consecutive points, no duplicates, valid L-shape corners).

Model object payloads tighten parentId: when it is a string (not null), it must have minLength: 1, so empty strings are invalid while null remains allowed for root-level objects. This appears on the related partial/required/full model schemas updated in the same diff.

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