fix: use pre-built zmx binaries to avoid zig2nix dependency
- Create custom package that downloads zmx binaries from zmx.sh
- Avoids zig2nix build issues on GitHub Actions x86_64 runner
- Add useGlobalPkgs to home-manager for consistent overlays
- Remove nixpkgs.enable from NixOS home configs
- Remove vscode config to eliminate nixpkgs.overlays warning
💘 Generated with Crush
Assisted-by: Claude Sonnet 4 via Crush <crush@charm.land>