Adds Docker setup and basic API endpoints

WHAT: Introduces Dockerfiles for development and production, Docker Compose configurations, a Makefile for common tasks, shell scripts for environment setup/teardown, a basic Express API with SQLite integration.
WHY: Enables easy setup and deployment of the application using Docker. Provides basic API endpoints for managing purchase items.
HOW:
- Creates `docker-compose.dev.yml` and `docker-compose.prod.yml` to define services and volumes.
- Introduces `Dockerfile.dev` and `Dockerfile.prod` to build container images with necessary dependencies.
- Adds `Makefile` with commands for building, running, and managing the application.
- Implements shell scripts for simplified Docker environment management.
- Sets up Express API with endpoints for CRUD operations on purchase items, using SQLite as the database.
- Uses `better-sqlite3` to connect and interact with the SQLite database.

docker/Dockerfile.prod

@@ -0,0 +1,26 @@
+FROM node:20-bullseye-slim
+ENV npm_config_registry=https://registry.npmmirror.com
+ENV npm_config_build_from_source=true
+
+# Build prerequisites for native modules (better-sqlite3)
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends python3 make g++ \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+# Install server deps in container (native modules match linux/amd64)
+COPY server/package.json ./server/package.json
+RUN cd server && npm install --omit=dev --build-from-source
+
+# Copy server runtime and prebuilt frontend from host
+COPY server/dist ./server/dist
+COPY dist ./frontend
+
+ENV PORT=8080
+ENV DB_PATH=/data/purchase.db
+
+EXPOSE 8080
+CMD ["node", "server/dist/index.js"]
+
+