Create and publish Porter PaaS local-first dev-stack repo

[mdheller]

Summary

Create SocioProphet/porter-paas as the local-first Porter PaaS integration/dev-stack repository.

Why

The archive work identified Porter PaaS as a local-first dev-stack integration lane. It should not be folded into SourceOS build substrate, agentplane, or socios; those systems should invoke/validate it through contracts and receipts.

Seed content to publish

Prepared sandbox payload includes:

• local-first dev-stack README / docs
• integration scaffolding for Porter-style app/service workflows
• boundary notes keeping agentplane as execution plane rather than dev-stack repo

Acceptance criteria

• Create SocioProphet/porter-paas
• Push prepared payload on an import branch
• Add README explaining boundary with agentplane/socios/sourceos-build
• Add smoke test / validation entrypoint
• Add receipt shape for local dev-stack runs
• Link from agentplane integration docs once repo exists

Non-goals

• Do not make porter-paas the agent execution plane
• Do not move SourceOS image build substrate into porter-paas
• Do not add secrets or provider credentials