feat: add initial Docker Compose infrastructure

docs/deployment.md

@@ -5,10 +5,12 @@ AzioneLab should deploy with a simple Docker Compose topology:
 - `nginx`: public reverse proxy and static frontend server;
 - `frontend`: Angular build source or build stage for static assets;
 - `backend`: Django 5.2 LTS application served by gunicorn;
-- `db`: PostgreSQL database.
+- `postgres`: PostgreSQL database.
 
 Only nginx should expose public ports. The backend and database should stay on the internal Compose network.
 
+The initial Compose setup is located at `infra/docker/compose.yml`.
+
 ## Services
 
 ### nginx
@@ -37,6 +39,8 @@ Deployment options:
 
 The first option is preferred for a simple production deployment because nginx can serve immutable built assets without a long-running Node process.
 
+At the infrastructure placeholder stage, the `frontend` service serves a static placeholder page with nginx. The Angular build will replace this placeholder later.
+
 ### backend
 
 The backend is a Django application served by gunicorn.
@@ -51,7 +55,9 @@ Responsibilities:
 
 The backend should run database migrations before or during deployment through an explicit operational command, not as hidden startup magic unless that choice is documented later.
 
-### db
+At the infrastructure placeholder stage, the `backend` service runs gunicorn against a minimal placeholder WSGI application. The real Django application will replace it later.
+
+### postgres
 
 PostgreSQL is the only database service.
 
@@ -84,6 +90,8 @@ Generated QR codes may also be generated on demand instead of stored as files. I
 
 ## Configuration
 
+Copy `.env.example` to `.env` and replace all placeholder values before running or deploying the stack.
+
 Required backend configuration:
 
 - `DJANGO_SECRET_KEY`;
@@ -129,21 +137,25 @@ The exact commands will be finalized when application code and Compose files are
 Expected production-style flow:
 
 ```bash
-docker compose build
-docker compose run --rm backend python manage.py migrate
-docker compose run --rm backend python manage.py collectstatic --noinput
-docker compose up -d
+docker compose --env-file .env -f infra/docker/compose.yml build
+docker compose --env-file .env -f infra/docker/compose.yml run --rm backend python manage.py migrate
+docker compose --env-file .env -f infra/docker/compose.yml run --rm backend python manage.py collectstatic --noinput
+docker compose --env-file .env -f infra/docker/compose.yml up -d
 ```
 
 Expected validation commands:
 
 ```bash
-docker compose config
-docker compose run --rm backend python manage.py check --deploy
-docker compose run --rm backend python manage.py test
+docker compose --env-file .env.example -f infra/docker/compose.yml config
+docker compose --env-file .env -f infra/docker/compose.yml run --rm backend python manage.py check --deploy
+docker compose --env-file .env -f infra/docker/compose.yml run --rm backend python manage.py test
 ```
 
-The repository does not yet define the canonical Docker-based test command.
+The canonical repository check for the current infrastructure stage is:
+
+```bash
+docker compose --env-file .env.example -f infra/docker/compose.yml config
+```
 
 ## Rollback