X 所有証明: 認証コード発行（30分有効・post_text と intent_url 付き。自前コード運用なら不要）
POST/v1/x/verify/code
X 所有証明: 認証コード発行（30分有効・post_text と intent_url 付き。自前コード運用なら不要）
Responses
- 200
- 400
- 401
- 403
- 429
- 500
OK
400 — code: invalid_json / invalid_parameter / invalid_prefix / prompt_required / quality_not_priced / size_not_priced / text_required / text_too_long / unknown_character / unsupported_format / unsupported_parameter
401 — code: invalid_user_token / not_authenticated / unauthorized
403 — code: account_too_new / card_required / enterprise_manual_approval / forbidden_scope / model_not_allowed / paid_requires_user_billing / request_over_key_cap / sponsor_stage_no_on_behalf / subject_required
429 — code: ip_daily_cap / rate_limited / user_daily_cap
500 — code: internal_error