Track CI/CD and supply chain phase

[codeforester]

Track the CI/CD and supply chain phase for Banyan Labs.

Intent:

• Expand the current test baseline into build, scan, package, and release automation.
• Add image builds, dependency/security checks, migration checks, and release artifact discipline as the product becomes deployable.
• Keep GitHub Actions as the first CI/CD system unless a later decision changes the delivery platform.

Completion direction:

• Pull requests prove test, build, and security quality.
• Release artifacts are reproducible and documented.
• Container images and service release notes are produced through automation.
• Detailed child issues are created only when this phase is ready to execute.

Related roadmap issue: #32.