add Dockerfile to build the go app

Dockerfile

@@ -0,0 +1,42 @@
+# Stage 1: Build the Go application
+FROM golang:1.23 AS builder
+
+ENV CGO_ENABLED=0
+ENV GOOS=linux
+ENV GOARCH=amd64
+
+WORKDIR /app
+
+# Copy the Go modules and dependencies
+COPY ./golang/go.mod ./golang/go.sum ./
+RUN go mod download
+
+# Copy the source code
+COPY ./golang/cmd ./cmd
+COPY ./golang/assets ./assets
+COPY ./golang/internal ./internal
+
+# Build the application
+RUN  go build -o main cmd/frontend/*
+
+# Stage 2: Run the application
+FROM alpine:latest
+
+ENV DB_HOST="10.99.0.3"
+ENV DB_PORT="5432"
+ENV DB_NAME="crowsnest"
+ENV DB_USER="crow"
+ENV DB_PASS=""
+
+# Set the working directory
+WORKDIR /app
+
+# Copy the built binary from the builder stage
+COPY --from=builder /app/main .
+COPY ./golang/assets ./assets
+
+# Expose the desired port (e.g., 8080)
+EXPOSE 8080
+
+# Command to run the application
+CMD ["/app/main"]