feat: regenerate API client from OpenAPI spec

[convoy-sdk-bot]

Automated regeneration via OpenAPI Generator (java/native) from docs/v3/openapi3.yaml on frain-dev/convoy main. Hand-written webhook verify (src/main/java/com/getconvoy/webhook/) is untouched by the sync script.

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Note

Low Risk
Generated-model Javadoc only; no runtime or serialization behavior changes in the provided diff.

Overview
Regenerates the Java API client from the updated OpenAPI spec (as described in the PR). The only visible diff updates Javadoc on ModelsCreateEvent#getEndpointId(): endpoint_id is documented as required unless the deprecated app_id field is supplied.

This is a documentation-only change in generated code—no field types, serializers, or API method signatures change in the shown diff.

^{Reviewed by Cursor Bugbot for commit 90b4d75. Bugbot is set up for automated code reviews on this repo. Configure here.}

[convoy-sdk-reviewer]

SDK reviewer app: approving a generated-paths-only diff on the regen branch. Auto-merge completes only after required status checks pass.

[mekilis]

SDK reviewer app: re-approving after permission upgrade; generated-paths-only diff on the regen branch.