Refactor project structure: modularized code into pkg and cmd directories, added unit tests, improved CI/CD pipeline, and enhanced documentation.

Dockerfile

@@ -1,11 +1,15 @@
+# syntax=docker/dockerfile:1
 FROM golang:1.26-alpine AS builder
 WORKDIR /app
-COPY . .
-RUN go build -o app
+COPY go.mod .
 
-FROM alpine:latest
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -o server ./cmd/diunwebhook/main.go
+
+FROM alpine:3.18
 WORKDIR /app
-COPY --from=builder /app/app .
+COPY --from=builder /app/server ./server
 COPY static ./static
 EXPOSE 8080
-CMD ["./app"]
+CMD ["./server"]