Feature/save signs (#2127)

* apply fix

* Fixes empty th:action

* Update build.gradle

* fix

* formatting

* Save signatures

* Fix code scanning alert no. 42: Uncontrolled data used in path expression

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

* fix UserServiceInterface

* Merge branch 'feature/saveSigns' of
git@github.com:Stirling-Tools/Stirling-PDF.git into feature/saveSigns

* 0.31.0 bump and further csrf

* formatting

* preview name

* add

* sign doc

* Update translation files (#2128)

Signed-off-by: GitHub Action <action@github.com>
Co-authored-by: GitHub Action <action@github.com>

---------

Signed-off-by: GitHub Action <action@github.com>
Co-authored-by: Dimitrios Kaitantzidis <james_k23@hotmail.gr>
Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>
Co-authored-by: a <a>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: GitHub Action <action@github.com>