BeforeUp 0.4.0 preview 1

BeforeUp 0.4.0 preview improves the reliability of Docker Compose host diagnostics and adds optional CI strictness.

Changes:

• Docker Desktop on Linux: detect the VM-backed daemon and skip workstation-side socket, mount and disk checks that cannot reliably describe the VM. Running-container metadata comparison remains available.
• Rootless Docker: warn about potentially restricted host ports and bind-source permissions that cannot be proven from path existence alone. Respect the host's unprivileged-port threshold where available.
• IPv6/IPv4: distinguish definite duplicate host-port bindings from cross-family wildcard overlap whose behavior depends on the host's networking configuration.
• --strict: return a nonzero exit code on warnings for CI, without changing finding severities.
• Visual: subtle transparent rounded corners on the README banner.
• Docs: practical rootless, Docker Desktop and CI guidance, with scope and limitations stated.

Verification on the maintainer's Debian 13 host:

• 46 Go tests, full integration tests, race checks and static vet.
• 14 synthetic Compose cases, including a regression for two services publishing the same default host port.
• Temporary IPv6 loopback listener and cross-family Docker Compose configuration/dry-run cases.
• An isolated, unprivileged rootless Docker Engine with read-only BeforeUp checks; no rootless application container was launched. The isolated daemon was stopped and removed.
• Linux amd64 and arm64 archives and .deb packages; amd64 .deb install, execution and removal on Debian 13, Ubuntu 24.04 and Ubuntu 26.04.
• SHA-256 release artifacts validated after publication.

Limitations: Docker Desktop Linux itself and an SELinux-enforcing host were not available for live integration tests. Real rootless bind-mount write access and privileged-port publication remain untested. ARM64 packaging was compiled, but not installed on real ARM64 hardware. This is a preview, not a guarantee of successful deployment.