ui(users): record last_login on /setup + sortable headers

internal/server/http/setup_handler.go

@@ -144,6 +144,10 @@ func (s *Server) handleUISetupPost(w stdhttp.ResponseWriter, r *stdhttp.Request)
 		Secure:   s.deps.Cfg.CookieSecure,
 		Expires:  now.Add(8 * time.Hour),
 	})
+	// Record the login so the users-list "Last login" column shows
+	// the moment they completed setup (the regular /login path does
+	// the same; we'd otherwise leave the row showing "never").
+	_ = s.deps.Store.MarkUserLogin(r.Context(), u.ID, now)
 	_ = s.deps.Store.AppendAudit(r.Context(), store.AuditEntry{
 		ID:         ulid.Make().String(),
 		UserID:     &u.ID,