feat: print git commit during startup

server/Dockerfile

@@ -1,10 +1,11 @@
 FROM golang:1.24.7 AS build
+ARG GIT_COMMIT=unknown
 WORKDIR /src
 COPY . .
 RUN --mount=type=cache,target=/go/pkg/mod \
     --mount=type=cache,target=/root/.cache/go-build \
     CGO_ENABLED=0 GOOS=linux GOARCH=amd64 \
-    go build -trimpath -ldflags="-s -w" \
+    go build -trimpath -ldflags="-s -w -X main.commit=${GIT_COMMIT}" \
     -o /out/server ./server/cmd/marka-server
 
 FROM scratch

server/cmd/marka-server/main.go

@@ -12,6 +12,8 @@ import (
 	"git.max-richter.dev/max/marka/server/internal/handler"
 )
 
+var commit = "unknown"
+
 type multi []string
 
 func (m *multi) String() string { return strings.Join(*m, ",") }
@@ -21,6 +23,7 @@ func (m *multi) Set(v string) error {
 }
 
 func main() {
+	log.Printf("marka-server, commit=%s", commit)
 	var roots multi
 	flag.Var(&roots, "root", "repeatable; specify multiple -root flags")
 	addr := flag.String("addr", ":8080", "listen address")