feat(server): multi-stage Dockerfile that builds Go from source

server/manifest/docker/Dockerfile

@@ -1,7 +1,37 @@
+# SPDX-FileCopyrightText: 2026 M5Stack Technology CO LTD
+# SPDX-License-Identifier: MIT
+#
+# Multi-stage build. Run from the server/ directory:
+#   cd server && docker build -t stackchan-server -f manifest/docker/Dockerfile .
+#
+# Or with docker compose using a Git URL context:
+#   build:
+#     context: https://github.com/m5stack/StackChan.git#main:server
+#     dockerfile: manifest/docker/Dockerfile
+
+FROM golang:1.24-alpine AS builder
+
+RUN apk add --no-cache gcc musl-dev sqlite-dev
+
+WORKDIR /src
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+
+ENV CGO_ENABLED=1 GOOS=linux
+RUN go build -trimpath -ldflags="-s -w" -o /out/stackChan main.go
+
 FROM alpine:latest
-ENV WORKDIR=/app
-WORKDIR $WORKDIR
-COPY ./stackChan $WORKDIR/stackChan
-COPY ./config.yaml $WORKDIR/config.yaml
-RUN chmod +x $WORKDIR/stackChan
-CMD ["./stackChan"]
+
+RUN apk add --no-cache ca-certificates tzdata
+
+WORKDIR /app
+
+COPY --from=builder /out/stackChan /app/stackChan
+COPY --from=builder /src/manifest/config/config.yaml /app/config.yaml
+
+EXPOSE 12800
+
+CMD ["/app/stackChan"]