Containerize backend with Docker Compose

Added Docker support for easy deployment:
- Dockerfile: Python 3.11 slim image with FastAPI app
- docker-compose.yml: Service definition with volume mounting for data persistence
- .dockerignore: Exclude unnecessary files from Docker build
- database.py: Updated to store SQLite DB in ./data directory for volume persistence
- .gitignore: Added entries for database files and data directory
- README.md: Comprehensive documentation with Docker and local setup instructions

The application can now be run with: docker compose up -d
Database persists in ./data directory mounted as a volume

docker-compose.yml

@@ -0,0 +1,23 @@
+version: '3.8'
+
+services:
+  seismo-backend:
+    build: .
+    container_name: seismo-fleet-manager
+    ports:
+      - "8000:8000"
+    volumes:
+      # Persist SQLite database
+      - ./data:/app/data
+    environment:
+      - PYTHONUNBUFFERED=1
+    restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8000/"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 40s
+
+volumes:
+  data: