feat: add Docker setup with Dockerfile and docker-compose

Co-authored-by: aider (openai/gpt-5) <aider@aider.chat>

docker-compose.yml

@@ -0,0 +1,29 @@
+version: "3.8"
+
+services:
+  app:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    image: ntp_timeturner:latest
+    container_name: ntp_timeturner
+    environment:
+      - RUST_LOG=info
+    ports:
+      - "8080:8080"
+    volumes:
+      - ./static:/app/static:ro
+    restart: unless-stopped
+
+  # Optional: probe a PTP hardware clock (Linux host with /dev/ptp0)
+  ptp-probe:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    image: ntp_timeturner:latest
+    profiles:
+      - hw
+    command: ["ptp_probe", "--device", "/dev/ptp0", "--interval", "1.0", "--count", "0"]
+    devices:
+      - "/dev/ptp0:/dev/ptp0"
+    restart: "no"