add Dockerfile + docker-compose: single-image deploy (nginx + backend)

Multi-stage build: node builds frontend dist, golang builds static
binary (modernc sqlite, CGO off), alpine runtime runs nginx :80 +
backend :8890 in one container. nginx serves SPA with fallback, strips
/api prefix (same as vite dev proxy), proxies protocol endpoints
(/mcp, /m/*, /v1/*, /d/*, /ws/*, *.php) with buffering off for
NDJSON/SSE streams and WS upgrade headers.

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Dockerfile

@@ -0,0 +1,33 @@
+# ---------- 前端构建 ----------
+FROM node:22-alpine AS web
+WORKDIR /app/frontend
+COPY frontend/package.json frontend/package-lock.json ./
+RUN npm ci --no-audit --no-fund
+COPY frontend/ .
+RUN npm run build
+
+# ---------- 后端构建 ----------
+FROM golang:1-alpine AS api
+WORKDIR /app/backend
+COPY backend/go.mod backend/go.sum ./
+RUN go mod download
+COPY backend/ .
+# modernc.org/sqlite 纯 Go 实现，零 CGO 静态二进制
+RUN CGO_ENABLED=0 go build -ldflags="-s -w" -o /cyibox ./cmd/server
+
+# ---------- 运行时 ----------
+FROM alpine:3.21
+RUN apk add --no-cache nginx ca-certificates tzdata
+WORKDIR /app
+COPY --from=api /cyibox /app/cyibox
+COPY --from=web /app/frontend/dist /app/web/dist
+COPY docker/nginx.conf /etc/nginx/http.d/default.conf
+COPY docker/entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh && mkdir -p /app/data
+
+ENV CYIBOX_PORT=8890 \
+    CYIBOX_DB=/app/data/cyibox.db
+
+EXPOSE 80
+VOLUME ["/app/data"]
+ENTRYPOINT ["/entrypoint.sh"]