Support the project deployment lifecycle through the Shopware PaaS CLI

[shyim]

Parent: #1553 (under #1009).

User story

As a developer deploying to Shopware PaaS, I want to create builds and activate them through the same project deployment commands, so that switching hosting models does not require a separate lifecycle workflow.

Dependencies and current status

Use the executor lifecycle contract from #1554 and shared history/rollback policy from #1557. The concrete PaaS backend is not implemented yet.

Acceptance criteria

• Add/select a PaaS project environment without changing existing local, Docker or SSH behavior; document the required target configuration.
• deployment create proxies sw-paas application build create and returns the resulting application-build ID as an opaque deployment reference.
• deployment rollout <reference> proxies sw-paas application deployment create --application-build-id <reference> and returns an application-deployment ID as the rollout reference.
• Use machine-readable PaaS CLI output to obtain references/history; do not parse human-formatted tables.
• Expose successful rollouts newest first with their application-build IDs and active state via the optional history capability.
• Reuse the command-layer rollback selection to create a new application deployment for an earlier application-build ID; do not rebuild the application.
• Discover the external sw-paas executable and give actionable errors when it is missing or unauthenticated. Reuse its authentication mechanism without copying credentials into project configuration.
• Forward cancellation and failures correctly, preserving useful diagnostics and keeping reference output distinguishable from CLI logs.
• Tests with a fake PaaS CLI cover argument mapping, references, malformed output, history, rollback and error/cancellation behavior without requiring a live PaaS account.
• Document whether the returned rollout reference indicates acceptance or completed activation; do not equate command acceptance with a healthy rollout.

Out of scope

A PaaS SDK embedded in shopware-cli, archive upload through the SSH backend, database rollback, and application-specific health/worker orchestration.

Readiness checklist

• Acceptance criteria are defined.
• Backward compatibility: deployment commands remain experimental behind the deployment build tag.
• User-facing help/documentation reviewed.
• Tests added or adjusted and reviewed.