Add version

Dockerfile

@@ -1,15 +1,24 @@
 FROM golang:1.27-alpine AS builder
 
+ARG VERSION=dev # maintained in build.sh
+ARG GIT_SHA=0
+
 WORKDIR /build
 
 COPY go.mod ./
 
 COPY index.html.tmpl main.go ./
 
-RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o beam .
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags "-X main.version=${VERSION}-${GIT_SHA}" -a -installsuffix cgo -o beam .
 
 FROM alpine:latest
 
+ARG VERSION=0.1.0
+ARG GIT_SHA=dev
+
+LABEL org.opencontainers.image.version="${VERSION}"
+LABEL org.opencontainers.image.revision="${GIT_SHA}"
+
 RUN apk add mailcap \
     && adduser -D -u 1000 beam \
     && mkdir /uploads \