Simplify and validate Docker deployment

Dockerfile

@@ -1,17 +1,28 @@
 FROM golang:1.26 AS build
+
 WORKDIR /src
 COPY go.mod ./
 RUN go mod download
 COPY . .
-RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /preface-tools ./cmd/preface-tools
-RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /healthcheck ./cmd/healthcheck
+RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /out/preface-tools ./cmd/preface-tools
+RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /out/healthcheck ./cmd/healthcheck
+
+FROM alpine:3.21
+
+RUN apk add --no-cache ca-certificates \
+    && addgroup -S -g 10001 preface \
+    && adduser -S -D -H -u 10001 -G preface preface
 
-FROM gcr.io/distroless/static-debian12:nonroot
 WORKDIR /app
-COPY --from=build /preface-tools /usr/local/bin/preface-tools
-COPY --from=build /healthcheck /usr/local/bin/healthcheck
-COPY --from=build /src/prompts /app/prompts
-VOLUME ["/app/data"]
+COPY --from=build /out/preface-tools /usr/local/bin/preface-tools
+COPY --from=build /out/healthcheck /usr/local/bin/healthcheck
+COPY --chown=preface:preface prompts /app/prompts
+RUN mkdir -p /app/data/comic-animator/uploads /app/data/comic-animator/outputs \
+    && chown -R preface:preface /app/data
+
+USER preface
 EXPOSE 8080
-HEALTHCHECK --interval=30s --timeout=3s --start-period=10s --retries=3 CMD ["/usr/local/bin/healthcheck", "http://127.0.0.1:8080/readyz"]
+HEALTHCHECK --interval=30s --timeout=3s --start-period=10s --retries=3 \
+    CMD ["/usr/local/bin/healthcheck", "http://127.0.0.1:8080/readyz"]
+
 ENTRYPOINT ["/usr/local/bin/preface-tools"]