Update Dockerfile to optimize build process and improve image size

Dockerfile

@@ -1,13 +1,29 @@
-FROM golang:1.22
+# Stage 1: Build the application
+FROM golang:1.22 AS builder
 
 WORKDIR /usr/src/app
 
-
 COPY go.mod go.sum ./
 RUN go mod download && go mod verify
 
 COPY . .
 RUN CGO_ENABLED=1 GOOS=linux go build -ldflags="-s -w" -buildvcs=false -o /donetick
+
+# Stage 2: Create a smaller runtime image
+FROM alpine:latest
+
+# Install necessary CA certificates
+RUN apk --no-cache add ca-certificates
+
+# Copy the binary and config folder from the builder stage
+COPY --from=builder /donetick /donetick
+COPY --from=builder /usr/src/app/config /config
+
+# Set environment variables
 ENV DT_ENV="selfhosted"
+
+# Expose the application port
 EXPOSE 2021
+
+# Command to run the application
 CMD ["/donetick"]