feat(release): add automated VFS builds for releases

[corylanou]

Summary

• Add VFS (SQLite loadable extension) builds to the release workflow
• Build for linux/amd64, linux/arm64, darwin/amd64, darwin/arm64
• VFS artifacts uploaded to same GitHub release as main binaries

Changes

Makefile

Added platform-specific VFS build targets:

• vfs-linux-amd64 - Native build on Linux x86_64
• vfs-linux-arm64 - Cross-compile using gcc-aarch64-linux-gnu
• vfs-darwin-amd64 - Native build on macOS Intel
• vfs-darwin-arm64 - Native build on macOS Apple Silicon

.github/workflows/release.yml

Added two new jobs that run after GoReleaser:

• vfs-build-linux - Matrix build for Linux (amd64, arm64)
• vfs-build-darwin - Matrix build for macOS (amd64 on macos-13, arm64 on macos-14)

Both jobs:

1. Wait for goreleaser job to complete
2. Build VFS extension using Makefile targets
3. Create tar.gz archive
4. Upload to existing release via gh release upload --clobber

.goreleaser.yml

Updated release notes header to document VFS extension availability.

Artifact Naming

litestream-vfs-{version}-{os}-{arch}.tar.gz

Contents:

• Linux: litestream-vfs-linux-{arch}.so
• macOS: litestream-vfs-darwin-{arch}.dylib

Test Plan

• Tested make vfs-darwin-arm64 locally - builds successfully
• Tested make vfs-darwin-amd64 locally - cross-compile works
• Linux builds will be verified in CI when a test release is created

Closes #863

[corylanou]

Local Testing Instructions

To verify the VFS builds locally, you can build all 4 platforms:

macOS Builds (native)

# Build macOS Intel (x86_64)
make vfs-darwin-amd64

# Build macOS Apple Silicon (arm64)
make vfs-darwin-arm64

Linux Builds (via Docker)

# Build both Linux architectures in Docker
docker run --rm --platform linux/amd64 -v $(pwd):/src -w /src golang:1.25rc1 bash -c "
  apt-get update && apt-get install -y gcc-aarch64-linux-gnu &&
  make vfs-linux-amd64 &&
  make vfs-linux-arm64
"

Note: The --platform linux/amd64 flag is required on Apple Silicon Macs to ensure the container runs in x86_64 mode with proper cross-compilation support.

Verify Build Artifacts

# Check all built artifacts
ls -la dist/litestream-vfs-*
file dist/litestream-vfs-*.so dist/litestream-vfs-*.dylib

Expected output:

Platform	File	Type
Linux x86_64	litestream-vfs-linux-amd64.so	ELF 64-bit LSB shared object, x86-64
Linux ARM64	litestream-vfs-linux-arm64.so	ELF 64-bit LSB shared object, ARM aarch64
macOS Intel	litestream-vfs-darwin-amd64.dylib	Mach-O 64-bit x86_64
macOS Apple Silicon	litestream-vfs-darwin-arm64.dylib	Mach-O 64-bit arm64

[benbjohnson]

That all looks good. The one change I'd make is to name the file in the tarball as litestream-vfs.so regardless of what platform it's built for.

Also, I think we should probably rename litestream-vfs.so to just litestream.so since the VFS is registered as "litestream" but we can do that in a separate PR.