The `INSTALL.txt` file has been removed, as all installation instructions are now exclusively maintained on the project wiki. This updates `README.md` and build artifacts to reflect this change.
Additionally, `COPYRIGHT.txt` has been updated to include a new active team member, streamline translation contributor credits, and provide a direct link to GNU licenses. A minor CSS adjustment for the mobile UI is also included.
This update improves the release workflow by:
* Configuring GitHub Actions `upload-artifact` to transfer files directly without unnecessary zipping, simplifying artifact retrieval for subsequent jobs.
* Integrating `pefile` to perform an Authenticode signature check on the Windows installer, ensuring all official releases are properly signed.
