TanStack AI adapter calls Mynth directly

Use the adapter without the SDK, configure a gateway or custom fetch, and build model selectors with display names and capabilities.

The TanStack AI adapter now calls the Mynth API directly and no longer needs @mynthio/sdk.

Configure baseURL, defaultHeaders, or a custom fetch for a gateway. MYNTH_IMAGE_MODEL_META provides model display names and capabilities, and isMynthImageModel() validates model IDs. The catalog includes Qwen Image 2.1 Pro and Gemini Nano Banana 2.1.

Error classes now come from @mynthio/tanstack-ai-adapter. Update imports that previously came from the SDK. Failed tasks throw MynthTaskFailedError with the task's errors. See the adapter documentation for the available error classes.