Upgrade github.com/docker/docker to v29 (CVE-2026-34040, CVE-2026-42306)

[michaelmcnees]

The Trivy scan on v0.5.1 found two HIGH CVEs fixed in docker/docker v29.3.1. v29 is not in the Go module proxy (+incompatible versioning). Both are in .trivyignore pending the upgrade. Remove ignore entries and run go get once v29 lands in the proxy.