fix(auth): export PasswordReset; keep the reset email's reassurance on one line (milestone 497)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

steward/models/__init__.py

@@ -14,7 +14,7 @@ from .settings import AppSetting
 from .dashboard import Dashboard, DashboardWidget, DashboardShareToken
 
 __all__ = [
-    "Base", "User", "ApiToken", "UserInvite",
+    "Base", "User", "ApiToken", "UserInvite", "PasswordReset",
     "Host",
     "Monitor", "MonitorResult", "MonitorType",
     "PluginMetric",

steward/templates/email/password_reset.txt

@@ -9,5 +9,5 @@ Link works until: {{ r.expires }}
 Choose a new password: {{ r.link }}
 
 --
-The link works once. If you didn't ask for this, ignore it: your password is
+The link works once.
-unchanged.
+If you didn't ask for this, ignore it: your password is unchanged.