Message "Error reason is 'NoSubscription' and no additional error information was provided (https://generators.ai.unity.com)." is thrown when entering a prompt

How to reproduce:

1. Create a new project
2. Install the AI Assistant package
3. Sign in to the Editor with an account that has an active paid AI subscription and available credits
4. Open the AI Assistant window
5. Observe the console and the Assistant panel

Actual result: Message "Error reason is 'NoSubscription'“ is thrown
Expected result: The Assistant loads normally

Reproducible with: 1.0.0-pre.2 (6000.3.11f1), 1.7.0-pre.1 (6000.3.11f1)

Reproducible on: Windows 11, macOS 26.3 Arm64
Not reproducible on: No other environments tested

Note: Error is returned by the backend service (generators.ai.unity.com), not local Editor code