Add error details to Distribution Release responses

The Distribution Release model returned by **Get Distribution Release** (`GET /projects/{projectId}/distributions/{hash}/release`, `api.projects.distributions.release.get`) and **Release Distribution** (`POST`, `api.projects.distributions.release.post`) now includes an optional `error` object:

- `error` — object with `message` (string); present only when the release `status` is `failed`

This applies to both file-based and string-based distribution releases, in both Crowdin and Crowdin Enterprise. Client libraries should add the field to the distribution release response models so consumers can surface release failures.

**References:**
- [Release Distribution](https://support.crowdin.com/developer/api/v2/#operation/api.projects.distributions.release.post)
- [Get Distribution Release](https://support.crowdin.com/developer/api/v2/#operation/api.projects.distributions.release.get)
- Crowdin Enterprise: [Get Distribution Release](https://support.crowdin.com/developer/enterprise/api/v2/#operation/api.projects.distributions.release.get)

Start with the response models and entry points for Get Distribution Release (api.projects.distributions.release.get) and Release Distribution (api.projects.distributions.release.post). Check how file-based and string-based releases are represented, then verify that failed releases can expose the optional error.message field in both Crowdin and Crowdin Enterprise responses.

Written by the indexing model from the issue text.