feat: add Docker image, production server and health check

- Multi-stage Dockerfile on node:24-slim, non-root, healthcheck, /app/data volume
- server.mjs wraps the Astro handler with brotli/gzip compression,
  security headers and graceful SIGTERM shutdown (npm start)
- GET /api/health/ reports server and view-counter DB status
- Move build-only packages to devDependencies (smaller runtime image)
- docker-compose.yml as an alternative for Dokploy Compose

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,30 @@
+# ta1sph.info — Astro static site + small Node server for /api/* (view counter).
+# Dokploy: Build Type "Dockerfile", container port 4321, volume at /app/data.
+
+# ---- build ----
+FROM node:24-slim AS build
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+COPY . .
+RUN npm run build && npm prune --omit=dev
+
+# ---- runtime ----
+FROM node:24-slim AS runtime
+WORKDIR /app
+ENV NODE_ENV=production \
+    HOST=0.0.0.0 \
+    PORT=4321 \
+    DATA_DIR=/app/data
+COPY --from=build --chown=node:node /app/package.json ./
+COPY --from=build --chown=node:node /app/node_modules ./node_modules
+COPY --from=build --chown=node:node /app/dist ./dist
+COPY --from=build --chown=node:node /app/server.mjs ./
+# Named volume mounted here keeps the view-counter database across deploys.
+RUN mkdir -p /app/data && chown node:node /app/data
+VOLUME ["/app/data"]
+USER node
+EXPOSE 4321
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+  CMD node -e "fetch('http://127.0.0.1:4321/api/health/').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))"
+CMD ["node", "server.mjs"]