feat: regenerate API client from OpenAPI spec

[convoy-sdk-bot]

Automated regeneration via openapi-python-client from docs/v3/openapi3.yaml on frain-dev/convoy main. Hand-written webhook verify (src/convoy/utils/) is untouched by the sync script.

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Note

Medium Risk
Removing metadata from two public event model types is a breaking SDK change for consumers; failure_reason is additive and low risk on its own.

Overview
Regenerated OpenAPI client models for event payloads: DatastoreEvent and ModelsEventResponse now expose failure_reason (operator-facing text for failed events) and no longer include the metadata string field.

Serialization (to_dict / from_dict) follows the same pattern as other optional string fields. Any code that read or wrote metadata on these two types must switch to the updated API shape or use additional_properties if the server still returns extra keys.

^{Reviewed by Cursor Bugbot for commit 89c7236. 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.