feat(batch-print): add headless batch print for pdf/docx/djvu/xps - #385

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-go@v3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

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Include file: <cups/ipp.h> not found. Please note: Cppcheck does not need standard library headers to get proper results.

Include file: <cups/cups.h> not found. Please note: Cppcheck does not need standard library headers to get proper results.

Include file: <QStringList> not found. Please note: Cppcheck does not need standard library headers to get proper results.

Include file: <QString> not found. Please note: Cppcheck does not need standard library headers to get proper results.

Class 'BatchPrintApp' does not have a operator= which is recommended since it has dynamic memory/resource allocation(s).

Class 'BatchPrintApp' does not have a copy constructor which is recommended since it has dynamic memory/resource allocation(s).

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