BeforeUp 0.4.3 preview 1

BeforeUp 0.4.3 preview — quality audit and focused correctness fixes.

Fixes:

• BUILD_CONTEXT_INVALID warns when an existing local build context is a file, not a directory.
• Added/removed published-port findings have deterministic ordering in text and JSON output.
• PORT_OWNERS_UNKNOWN warns when Docker cannot inspect published-port ownership. BeforeUp no longer claims ports are clear merely because ss shows no listener.
• Regression from the interrupted review is now part of build_test.go, not a stranded review artifact.
• Python cache files are ignored; changelog and platform documentation updated.

Broader audit:

• Reviewed CLI behavior, Docker command boundaries, report redaction, deterministic output, module/dependency structure, packaging/test scripts and documentation.
• 57 Go tests, repeated deterministic-order checks, race detector, vet, make check, Go module verification and Docker Compose integration all passed.
• 14 reproducible Docker Compose cases passed and a read-only comparison against an existing Docker service returned no blockers.
• All tracked shell scripts passed POSIX sh syntax validation; Python fixture source passed parsing.
• Source documentation passed strict prose checks with zero warnings; Go statement coverage is 83.1%.
• AMD64 and ARM64 static Linux archives and .deb packages built; AMD64 .deb installed and removed on Debian 13 and Ubuntu 24.04/26.04.

This is a preview, not universal certification. Real Docker Desktop Linux, SELinux enforcing, rootless application write paths, IPv6 configurations beyond tested cases and native ARM64 package installation remain outside verified scope.