Release 0.2.8

[overwrite00]

Summary

• Fix stable release packaging so stable artifacts are rebuilt from main with stable version metadata.
• Stop republishing beta-built binaries as stable assets.
• Add artifact checks to fail stable builds if beta suffixes appear in generated filenames.

Validation

• npm --prefix electron audit --audit-level=low
• npm --prefix frontend run build
• python\.venv\Scripts\python.exe -m pytest python/tests/ -v
• npm --prefix electron run make -- --skip-package=false
• GitHub Actions Build & Release: success on develop
• GitHub Actions CodeQL: success on develop