Method cleanup

tests/test_validation.cpp:166–170

    }

    void cleanup() {
        delete m_ctrl;  m_ctrl = nullptr; m_editor = nullptr;
        delete m_splitter; m_splitter = nullptr;
        delete m_doc; m_doc = nullptr;
    }

    // ════════════════════════════════════════════════════════
    // Pure parsing/validation tests (no GUI interaction)