test: login gates, password-changed sources and the reset action

- TestLoginGates: registry order, first result or error wins, nil gates,
  concurrent Add and Check, CheckLoginGates without a registry
- TestLoginGateOrder: refused first factors never reach a gate, rehash
  before a challenge, restore and reactivate mail only after the gates,
  gate answers pass through, refresh never asks a gate
- TestPasswordChangedSources: reset, change and admin set fire once inside
  the write's transaction; rehash and registration fire none
- TestResetTwoFactorAction: offered only with a service and a factor,
  danger, permission, transaction and rollback

README.md

@@ -353,4 +353,6 @@ go test ./...           # full run, starts Postgres with testcontainers (needs D
 
 `TestMemberTokenScopesBoot` (no Docker) checks that the scope Boot step fails for a name two plugins declare (naming both), for a redeclared `read`, `write` or `ai`, for a bad name, an empty label and a missing phrase key. With Docker: `TestMemberTokenScopes` walks the member token scope acceptance list item by item (mint and `middleware.Scope`, the 403 message, the 422 for an undeclared scope, the list, discovery in en and pl, the per-application catalog and the legacy fallback); `TestBackendLinkAuthTime` checks the link proof against login, request, refresh and re-login orders, a token without `auth_time` and another user's session token; `TestBackendLinkShowPost` checks that `POST /backend-link/show` answers like the GET route with `Cache-Control: no-store, private`, the fragment URL and `backend_links.page_path`; `TestAccessRevocation` checks `AccessRevokedEvent` from the ban action, the password reset, the password change and an administrator setting a password (ids, `Before`, reason, the transaction, the subject event after commit, the rollback on a failing listener) and that a banned user loses the backend link until unbanned; `TestUserMCPGuardClientIP` checks `last_used_ip` on the MCP personal-token path; `TestAPITokenRevokeEvent` checks the token-specific revoked event of `DELETE /tokens/{id}`; `TestOrganisationLogo` checks the logo field, the upload, `OrganisationLogoFields` with and without a logo, the URL fallback when the thumbnail fails, and that deleting an organisation removes its avatar and logo attachments, the rows and, once the delete commits, the blobs and thumbnails.
 
+The login-gate seam, the password-change hook and the Reset 2FA slot have their own tests. `TestLoginGates` (in `-short`, clean under `-race`) pins the registry: a nil or empty registry allows, gates run in the order they were added, the first result or error wins and stops the chain, nil gates are ignored, and `controllers.CheckLoginGates` allows when no registry is published. `TestLoginGateOrder` pins where `POST /login` asks the gates: refused first factors (wrong password, unknown email, not activated, banned) never reach them; the gate sees the attempt with the body already read; the bcrypt rehash happens before a challenge and fires no password-change event; a challenged deactivated account stays deactivated with no mail and no login event, while an allowed one is restored with one reactivate mail and one login event; a gate's status and body pass through; `/refresh` never asks a gate. `TestPasswordChangedSources` checks that the reset, the user's own change and an administrator setting a password each fire one `AccessRevokedEvent` with `PasswordChanged()` true inside the write's transaction (a listener's write through `ev.Tx` commits with it, a listener error rolls both back), and that the rehash and a registration fire none. `TestResetTwoFactorAction` covers the `reset_two_factor` record action: not offered without a published `classes.TwoFactorAdmin`, offered with the danger confirmation when one reports a second factor, hidden when it reports none, refused without `golem15.users.reset_two_factor`, `Run` refused outside the action's transaction, `Reset` committed with the action and rolled back by its error. The plan 01 smoke tests (`TestLoginGatesSmoke`, `TestLoginGateSmoke`, `TestPasswordChangedEventSmoke`, `TestResetTwoFactorSlotSmoke`) stay. The Postgres tests need Docker.
+
 The admin tests (`TestAdmin*`) boot the plugin with the admin API mounted on a database of their own and sign in backend administrators with a chosen permission set; the helpers are in `admin_harness_test.go`.