feat(cabana): add the My account page with subtitle and password change

- lagoon: 202610090001_backend_users_metadata adds WinterCMS's nullable
  jsonable backend_users.metadata column (TEXT); rollback drops only it
- cabana.BackendUser.Metadata and Subtitle read metadata.subtitle leniently
  (NULL, blank, null, [], invalid JSON and non-strings read as empty)
- GET /auth/me returns subtitle; PUT /account edits the signed-in admin's
  own names, email and subtitle, and the password with current_password;
  any other key is a 422 and nothing is written
- email: required, valid, 6-255 chars, unique against other admins' email
  and login ignoring case (soft-deleted included); a unique-index race is 422
- a password change sets tokens_valid_after, revokes the presented token and
  gives a cookie session a fresh cookie
- swag annotation, regenerated admin.json and schema.d.ts; route inventories,
  CSRF walk (27) and OpenAPI conformance learn the route
- SPA: My account item in the user menu opens /account (AccountView), which
  saves through PUT /account and updates the top bar via setCurrentUser
- backend::lang.myaccount strings (en, pl), rebuilt boardwalk dist
- cabana and lagoon READMEs, users-and-permissions and admin-spa docs

modules/phrasebook/backend/lang/en/lang.yaml

@@ -229,3 +229,22 @@ permissioneditor:
   locked: You cannot change this permission.
   empty: No permissions are defined yet.
   other: Other
+myaccount:
+  menu_label: My account
+  menu_description: Edit your name, email, subtitle and password.
+  profile: Profile
+  login: Login
+  first_name: First name
+  last_name: Last name
+  email: Email
+  subtitle: Subtitle
+  subtitle_comment: A short line shown under your name, for example your role or position.
+  password_section: Change password
+  password_comment: Leave blank to keep the current password.
+  current_password: Current password
+  password: New password
+  password_confirmation: Confirm new password
+  current_password_invalid: The current password is incorrect.
+  field_not_editable: This field cannot be changed on My account.
+  subtitle_unavailable: The subtitle cannot be saved because the stored profile metadata is not a JSON object.
+  saved: Account saved

modules/phrasebook/backend/lang/pl/lang.yaml

@@ -251,3 +251,22 @@ permissioneditor:
   locked: Nie możesz zmienić tego uprawnienia.
   empty: Nie zdefiniowano jeszcze żadnych uprawnień.
   other: Inne
+myaccount:
+  menu_label: Moje konto
+  menu_description: Zmień imię, nazwisko, e-mail, podtytuł i hasło.
+  profile: Profil
+  login: Login
+  first_name: Imię
+  last_name: Nazwisko
+  email: E-mail
+  subtitle: Podtytuł
+  subtitle_comment: Krótki opis pod Twoim imieniem, na przykład rola lub stanowisko.
+  password_section: Zmiana hasła
+  password_comment: Pozostaw puste, aby zachować obecne hasło.
+  current_password: Obecne hasło
+  password: Nowe hasło
+  password_confirmation: Powtórz nowe hasło
+  current_password_invalid: Obecne hasło jest nieprawidłowe.
+  field_not_editable: Tego pola nie można zmienić w ustawieniach konta.
+  subtitle_unavailable: Nie można zapisać podtytułu, ponieważ zapisane metadane profilu nie są obiektem JSON.
+  saved: Zapisano konto