At logout time, if the user authenticated via OIDC, we look up the
provider's `end_session_endpoint` (already discovered by Goth from the
OIDC metadata) and redirect there with `client_id` and
`post_logout_redirect_uri`.
Non-OIDC OAuth2 providers (GitHub, GitLab, etc.) are unaffected — they
fall back to local-only logout.
Fix#14270
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Signed-off-by: Nikita Vakula <nikita.vakula@alpsalpine.com>
Co-authored-by: Nikita Vakula <nikita.vakula@alpsalpine.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>