Initial cloud-services repo - gateway service + pkg modules

Dockerfile

@@ -0,0 +1,35 @@
+# Multi-service Dockerfile with build caching
+# Usage: docker build --build-arg SERVICE=gateway -t cloud-gateway .
+
+ARG SERVICE=gateway
+
+# Build stage
+FROM golang:1.24-alpine AS builder
+
+RUN apk add --no-cache git ca-certificates
+
+WORKDIR /src
+
+# Cache dependencies first (changes less often)
+COPY go.work go.work.sum* ./
+COPY pkg/go.mod pkg/go.sum* ./pkg/
+COPY services/${SERVICE}/go.mod services/${SERVICE}/go.sum* ./services/${SERVICE}/
+
+RUN go mod download
+
+# Copy source and build
+COPY pkg/ ./pkg/
+COPY services/${SERVICE}/ ./services/${SERVICE}/
+
+WORKDIR /src/services/${SERVICE}
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /app .
+
+# Runtime stage
+FROM alpine:3.20
+
+RUN apk add --no-cache ca-certificates tzdata
+
+COPY --from=builder /app /app
+
+USER nobody:nobody
+ENTRYPOINT ["/app"]