build: add docker setup

Dockerfile

@@ -0,0 +1,20 @@
+FROM golang:1.25.3-alpine AS builder
+
+WORKDIR /app
+COPY .  .
+
+# Build
+RUN go mod download
+RUN CGO_ENABLED=0 GOOS=linux go build -a -o main ./cmd/server
+###########
+
+FROM alpine:3.22.2
+
+RUN apk --no-cache add ca-certificates
+WORKDIR /root/
+
+# Copy the pre-built binary
+COPY --from=builder /app/main .
+
+EXPOSE 8080
+CMD ["./main"]