Update AI Prompts - remove deprecated assist action and add context fields

The Crowdin API updates the **AI** resource (prompts and prompt completions) in both Crowdin and Crowdin Enterprise. API client libraries should be updated accordingly.

**Remove deprecated `assist` action (breaking):**

- The previously deprecated `assist` AI prompt action is fully removed: it is dropped from the prompt `action` enum, and the related `assist` prompt-completion resource and override-prompt-values schemas are removed. Clients should drop `assist` from any prompt action handling.

**New context fields:**

- AI prompt forms: `projectContext` replaces the now-deprecated old project-context field, and prompt completion forms add `projectDescription` (deprecating the prior field).
- Enterprise basic-mode prompt configs (`pre_translate`, `alignment`, `qa_check`) gain an `organizationContext` flag to include the organization name and internal description in the prompt context, with corresponding enterprise prompt-completion override-prompt-values resources.

**References:**
- [AI](https://support.crowdin.com/developer/api/v2/#tag/AI)
- Crowdin Enterprise: [AI](https://support.crowdin.com/developer/enterprise/api/v2/#tag/AI)

Start with the Crowdin API AI references linked in the issue, then locate the Go client’s AI resource models and schemas. Update the prompt and prompt-completion representations for the removed assist action and the listed context fields, including Enterprise basic-mode configuration, and verify the generated client matches both Crowdin and Crowdin Enterprise API definitions.

Written by the indexing model from the issue text.