fix: KF6Attica recipe, kf6-knewstuff Attica dep, topo-sort cycle error

- Created kf6-attica recipe (minimal core library build providing
  KF6::Attica cmake target, needed by kf6-knewstuff). v6.10.0,
  QML/tests/examples disabled.
- Added kf6-attica to redbear-full.toml config, integrate-redbear.sh
  symlink, and recipes/kde/ symlink.
- Fixed kf6-knewstuff: removed stale find_package(KF6Attica)
  suppression; added kf6-attica as dependency. Now publishes
  to repo (core-only build produces empty package — upstream
  code structure yields no libs with QtQuick/widgets/tools off).
- Cookbook topo-sort: changed cycle fallback from silent
  Ok(recipes) to Err(Recursion) — surfaces dependency graph
  bugs instead of hiding them.
- Fixed stale QtNetwork comment: QtNetwork IS enabled in qtbase
  since 2026-04-29 (relibc DNS resolver hardened).
- Verified: kf6-attica builds, kf6-knewstuff publishes to repo

local/recipes/kde/kf6-attica/source/.gitlab-ci.yml

@@ -0,0 +1,11 @@
+# SPDX-FileCopyrightText: 2020 Volker Krause <vkrause@kde.org>
+# SPDX-License-Identifier: CC0-1.0
+
+include:
+  - project: sysadmin/ci-utilities
+    file:
+      - /gitlab-templates/linux-qt6.yml
+      - /gitlab-templates/android-qt6.yml
+      - /gitlab-templates/freebsd-qt6.yml
+      - /gitlab-templates/windows-qt6.yml
+      - /gitlab-templates/alpine-qt6.yml