two type hints introduced earlier on this branch referenced
classes by their fully-qualified names inline. hoist them to
the top-of-file use block per backend-context.md PHP rules.
Text now requires a User on construction. seed a user in
each test setUp that creates a Text directly or through the
fake repository so the suite remains green.
Forcing every call site to be explicit about admin status and
password eliminates a class of bugs where an unintended
isAdmin=false or empty passwordHash could silently slip through.
The CreateUserTest case that asserted the isAdmin default is
dropped since the default no longer exists.
