Expose ImageRecognitionRuntime.available() and gate the image-task pre-step
injection on it, so the capability is dormant until an endpoint is
configured instead of guiding the model to a call that can only fail.
Co-Authored-By: Claude <noreply@anthropic.com>
Service Definition for ctx.imageRecognition: a provider registry and
provider-selecting execution, mirrored on the web seam (duplicate ids
rejected, order-independent selection, ImageRecognitionError taxonomy).
Co-Authored-By: Claude <noreply@anthropic.com>