Removed DeterminateSystems/magic-nix-cache-action to resolve "Cannot convert ArchOs (amd64-linux)" error in Gitea Actions. The action is GitHub-specific and doesn't work with act_runner's platform detection. Workflow will now use default cache.nixos.org substituter.
Note: Consider migrating to Attic binary cache for better performance in the future.
- Add Magic Nix Cache for 3-9x faster builds
- Add --use-github-releases to only update stable versions
- Remove SKIP_PACKAGES, use dynamic discovery via passthru.updateScript
- Implement 4 concurrent update jobs for 4x speedup
- Add nix flake check for comprehensive validation
- Collect all build failures instead of failing on first
- Fix git reset bug that was destroying commits
- Add job timeout to prevent hanging
- Add detailed job summary and log artifacts
