feat: add containerized FastAPI health check

README.md

@@ -49,7 +49,41 @@ Each stage should produce a small, working, reviewable commit.
 
 ## Local development
 
-Local setup instructions will be added with the first application container.
+The current milestone is a minimal FastAPI application running in a hardened
+local container. Docker publishes it only on the PC's loopback interface, so it
+is not exposed to other devices on the LAN.
+
+Build and start it:
+
+```bash
+docker compose up --build -d
+```
+
+Check its status and logs:
+
+```bash
+docker compose ps
+docker compose logs --tail=50 web
+```
+
+Open <http://127.0.0.1:8000> or request the health endpoint:
+
+```bash
+curl --fail http://127.0.0.1:8000/health
+```
+
+Run the automated tests in an ephemeral container:
+
+```bash
+docker compose run --rm --build test
+```
+
+Stop the application:
+
+```bash
+docker compose down
+```
+
 Runtime data, downloaded media, local environment files, and secrets must not
 be committed to Git.