[Deploy-S3] WindowsServicePort -> OsServicePort + SystemdAdapter

[rickylabs]

Scope

Generalize the Windows-only WindowsServicePort to an OS-agnostic OsServicePort with two adapters: keep the existing ServyCliAdapter for Windows, add a SystemdAdapter for Linux. Removes the if (!Windows) abort guard in the deploy command path.

Target / adapter

Bare-metal (Linux systemd + Windows SERVY).

Acceptance criteria

• OsServicePort interface + ServyCliAdapter (Windows) + SystemdAdapter (Linux systemd unit install/enable/start/stop/status).
• Deploy command routes by host OS; Windows behaviour unchanged.
• Unit tests for both adapters (systemd unit rendering; servy path preserved).
• deno task check green.

Dependencies

S1 (deploy.targets.* contract — needs deploy.targets.linux/.windows shapes). Phase 1.

Tier / phase

BETA · Phase 1 · milestone 0.0.1-beta.1

Parent epic: #327