Add TeXstudio (Qt6 build by mlmateos)

[mlmateos]

TeXstudio Qt6 AppImage

• Version: 4.9.6-alpha1
• Qt: 6.x (requires glibc ≥ 2.34)
• Features: PDF viewer with Poppler-Qt6, GPG signed, native SyncTeX
• Requirements: Ubuntu 23.10+, Fedora 38+, or distros with glibc ≥ 2.34
• Note: Does not include TeX distribution; TeX Live must be installed separately

Release: https://github.com/mlmateos/texstudio-builds/releases/tag/v4.9.6-alpha1

[mlmateos]

@probono @TheAssassin This is an intentional Qt6-based build of TeXstudio, targeting modern Linux distributions (glibc ≥ 2.34, Ubuntu 23.10+, Fedora 38+, Debian 12+).

The automated test fails at the screenshot step because the CI environment uses Ubuntu 20.04 as a base, which is incompatible with Qt6's system requirements. This is expected behavior for a Qt6 AppImage.

Build validation:

• ✅ Compiles successfully from source with Qt6 and Poppler-Qt6
• ✅ Runs correctly on modern distributions (tested on Ubuntu 24.04)
• ✅ Includes GPG signature and SHA256 checksum for integrity verification
• ✅ Follows AppImage best practices (AppDir structure, desktop file, icon bundling)

Note: Users must have TeX Live or MiKTeX installed separately for PDF/LaTeX compilation features.

Release: https://github.com/mlmateos/texstudio-builds/releases/tag/v4.9.6-alpha1

Could you please review manually and approve for inclusion? This build is intended for users on modern systems who want the latest Qt6 features. Thank you! 🙏

[mlmateos]

Friendly ping 👋 Just checking if this PR needs any additional information. Happy to help if needed!