Adds linux-g++ build with:
- System dependencies: build-essential, libgl1-mesa-dev, zlib1g-dev
- Searches common Qt installation paths for gcc_64
Requires an Ubuntu runner with label "ubuntu" and Qt installed.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- ci.yml: Build on every push (for testing)
- release.yml: Full release pipeline on version tags
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>