Add Docker Compose and backend Dockerfile

Include .gitignore, go.mod/go.sum, initial Go source, init.sql, and
Docker‑Compose
configuration for the MSSQL and backend services.

backend/Dockerfile

@@ -0,0 +1,34 @@
+# Use the official Go image as the base image
+FROM golang:1.22-alpine AS builder
+
+# Set the working directory inside the container
+WORKDIR /app
+
+# Cache Go modules
+COPY go.mod ./
+RUN apk add --no-cache git
+RUN go mod download
+
+# Copy the source code
+COPY . .
+
+# Build the Go binary
+RUN go build -o main .
+
+# ---- Runtime image ----
+FROM alpine:3.19
+
+# Install ca-certificates (if needed)
+RUN apk add --no-cache ca-certificates
+
+# Set workdir
+WORKDIR /app
+
+# Copy the binary from the builder stage
+COPY --from=builder /app/main .
+
+# Expose the application port (default for the Go server)
+EXPOSE 8080
+
+# Command to run the binary
+CMD ["./main"]