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

backend/README.md

@@ -2,29 +2,37 @@
 
 FastAPI + PostgreSQL + Alembic.
 
-## Локальная разработка (без Docker)
+## Production (native на Ubuntu 24.04)
+
+См. **[docs/install-ubuntu-24.04-native.md](../docs/install-ubuntu-24.04-native.md)**.
+
+Кратко:
+
+```bash
+cd /opt/security-alert-center/backend
+python3.12 -m venv .venv && .venv/bin/pip install -r requirements.txt
+# /etc/security-alert-center/sac-api.env — см. deploy/env.native.example
+alembic upgrade head
+systemctl start sac-api
+```
+
+## Локальная разработка
 
 ```bash
 cd backend
 python3.12 -m venv .venv
-source .venv/bin/activate   # Windows: .venv\Scripts\activate
+source .venv/bin/activate
 pip install -r requirements.txt
 export DATABASE_URL=postgresql+psycopg2://sac:sac@localhost:5432/sac
-export SAC_BOOTSTRAP_API_KEY=sac_dev_test_key_change_me
+export SAC_BOOTSTRAP_API_KEY=sac_dev_test_key
+export EVENT_SCHEMA_PATH=../schemas/event-schema-v1.json
 alembic upgrade head
 uvicorn app.main:app --reload --port 8000
 ```
 
-## Docker (из корня репозитория)
+## Docker (альтернатива)
 
-```bash
-cd deploy
-cp .env.example .env
-# отредактировать .env
-docker compose up -d
-docker compose run --rm migrate
-curl http://127.0.0.1:8000/health
-```
+[docs/install-ubuntu-24.04-docker.md](../docs/install-ubuntu-24.04-docker.md)
 
 ## API
 
@@ -32,5 +40,3 @@ curl http://127.0.0.1:8000/health
 |-------|------|------|
 | GET | `/health` | нет |
 | POST | `/api/v1/events` | Bearer API key |
-
-См. [docs/agent-integration.md](../docs/agent-integration.md) и [docs/event-schema-v1.json](../docs/event-schema-v1.json).