feat: Add Dockerization support

Dockerfile

@@ -0,0 +1,44 @@
+# Build stage
+FROM rust:alpine AS builder
+
+# Install build dependencies
+RUN apk add --no-cache musl-dev
+
+WORKDIR /usr/src/dhl
+
+# 1. Copy only the dependency manifests
+COPY Cargo.toml Cargo.lock ./
+
+# 2. Create a dummy source file to build dependencies
+RUN mkdir src && echo "fn main() {}" > src/main.rs && \
+    cargo build --release && \
+    rm -rf src
+
+# 3. Now copy the real source code
+COPY src ./src
+
+# 4. Build the actual application
+# We touch the main file to ensure cargo rebuilds it
+RUN touch src/main.rs && cargo build --release
+
+# Final stage
+FROM alpine:latest
+
+# Set environment variable to signal the app it's running in Docker
+ENV DOCKER_CONTAINER=true
+
+# Install runtime dependencies
+RUN apk add --no-cache ca-certificates
+
+WORKDIR /app
+
+# Copy the binary from the builder stage
+COPY --from=builder /usr/src/dhl/target/release/dhl /usr/local/bin/dhl
+
+# Volume for configuration and response files
+VOLUME ["/app"]
+
+# Default port
+EXPOSE 3000
+
+CMD ["dhl"]