Add pre-built Nebraska binaries to GitHub release assets

[ervcz]

Add pre-built Nebraska binaries to GitHub releases to support users who need to run Nebraska without Docker.

Motivation

• Simplify deployment for non-Docker environments
• Remove build dependencies (Go, Node.js) requirement
• Enable lightweight installations and easier CI/CD integration

Proposed Assets

• Platform binaries: Linux (amd64/arm64), macOS (Intel/ARM), Windows
• Static frontend assets (tar.gz)
• SHA256 checksums file

Implementation Guidelines

• Extend GitHub Actions workflow for automated builds
• Consider using build tools like goreleaser for cross-platform compilation
• Include basic setup instructions with releases
• Document PostgreSQL requirements

Example Usage

wget /nebraska-linux-amd64 wget /nebraska-static-assets.tar.gz tar -xzf nebraska-static-assets.tar.gz ./nebraska-linux-amd64 -http-static-dir=./static