feat(openai): add gpt-5.1 and gpt-5.2 model identifiers #1274

Is your feature request related to a problem? Please describe.

When configuring OpenAI models using the Inngest JavaScript SDK, newer incremental GPT-5 model versions such as gpt-5.1 and gpt-5.2 are not currently included in the Model type union.
While the SDK intentionally supports arbitrary strings for forward compatibility, the absence of these officially released model identifiers limits autocomplete, discoverability, and type safety for developers using TypeScript.

Describe the solution you'd like

Extend the Model union type to explicitly include the stable, officially released OpenAI model identifiers:

• gpt-5.1
• gpt-5.2

This change would be additive and backward compatible, improving developer experience without introducing any runtime or behavioral changes.

Describe alternatives you've considered

• Relying exclusively on the (string & {}) fallback, which maintains compatibility but does not provide explicit typing or IDE autocomplete for newly released models.
• Adding speculative or undocumented variants (for example, size-based or preview suffixes), which was intentionally avoided to keep the SDK aligned with documented and stable OpenAI model identifiers.

Additional context

• The SDK already follows a clear pattern of listing stable OpenAI model identifiers while preserving forward compatibility.
• Incremental model versions (such as gpt-4.1) have been added previously for the same reason.
• This proposal aligns with existing naming conventions and does not introduce breaking changes or assumptions about future variants.