docs: native Ubuntu install as primary; systemd and nginx

- install-ubuntu-24.04-native.md (production) and -docker.md (alternative)

- deploy/systemd/sac-api.service, nginx/sac.conf.example, env.native.example

- deployment, README, INDEX, work-plan, TZ updated

docs/TZ.md

@@ -235,7 +235,7 @@ flowchart LR
 | Frontend | Vue 3 + Vite, UI-kit (Naive UI / PrimeVue), ECharts |
 | Realtime | Server-Sent Events (приоритет MVP) |
 | Reverse proxy | nginx |
-| Развёртывание | Docker Compose **или** native systemd (на выбор при реализации) |
+| Развёртывание | **Native:** PostgreSQL + systemd + nginx (production). Docker Compose — альтернатива для стенда |
 
 Детали — [architecture.md](architecture.md).