* Fix OIDC household invitation (issue #900)
- Auto-add existing user when inviting by email (no invite email sent)
- Accept page: choose 'Create account' or 'Sign in' (supports OIDC)
- Store invitation token in session on sign-in; accept after login (password,
OIDC, OIDC link, OIDC JIT, MFA)
- Invitation#accept_for!(user): add user to household and mark accepted
- Defensive guards: nil/blank user, token normalization, accept_for! return check
* Address PR review: rename accept_for! to accept_for, i18n OIDC notice, test fixes, stub Rails.application.config
* Fix flaky system test: assert only configure step, not flash message
Co-authored-by: Cursor <cursoragent@cursor.com>
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Signed-off-by: Juan José Mata <juanjo.mata@gmail.com>
Co-authored-by: mkdev11 <jaysmth689+github@users.noreply.github.com>
Co-authored-by: Juan José Mata <juanjo.mata@gmail.com>
Co-authored-by: Cursor <cursoragent@cursor.com>