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# BCP 47 support in article upserts

The `language` field on the article object in the upsert API now supports BCP 47 language tags (e.g., `en-CA`, `fr-FR`). The previously supported `locale` field is deprecated but still accepted for backwards compatibility if `language` is not provided.

API responses from `GET /v2/knowledge/articles` and `GET /v2/knowledge/articles/{id}` will continue to return `locale`, but it is no longer documented. In these responses, the `language` field contains the ISO 639-1 two-character language code, not the full BCP 47 tag.

This is part of a gradual migration. Eventually, `locale` will be removed from both persisted records and API responses, and `language` will consistently use BCP 47 tags across all endpoints.