feat: add Docker deployment support

- Multi-stage Dockerfile (Node build + Go build + Alpine runtime)
- docker-compose.yml with named volume for data persistence
- In-container Nginx reverse proxy (static files + API)
- Entrypoint script for graceful process management
- .dockerignore for optimized build context
- Updated README (zh/en) with Docker quick start and deployment docs

Closes #14

deploy/docker/entrypoint.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+set -e
+
+# Backend listens on internal port 8341, Nginx exposes 8340
+export BACKUPX_SERVER_PORT="${BACKUPX_SERVER_PORT_INTERNAL:-8341}"
+
+# Start Nginx in background
+nginx -g "daemon off;" &
+NGINX_PID=$!
+
+# Start BackupX backend
+/app/bin/backupx &
+APP_PID=$!
+
+# Trap signals for graceful shutdown
+trap 'kill $APP_PID $NGINX_PID 2>/dev/null; wait $APP_PID $NGINX_PID 2>/dev/null' SIGTERM SIGINT
+
+echo "BackupX started — Nginx :8340 -> Backend :8341"
+
+# Wait for either process to exit
+wait -n $APP_PID $NGINX_PID 2>/dev/null || true
+kill $APP_PID $NGINX_PID 2>/dev/null || true
+wait $APP_PID $NGINX_PID 2>/dev/null || true

deploy/docker/nginx.conf

@@ -0,0 +1,32 @@
+server {
+    listen 8340;
+    server_name _;
+
+    root /app/web;
+    index index.html;
+
+    # API reverse proxy to backend
+    location /api/ {
+        proxy_pass http://127.0.0.1:8341/api/;
+        proxy_http_version 1.1;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+        proxy_set_header Connection "";
+        proxy_buffering off;
+        proxy_cache off;
+        proxy_read_timeout 3600s;
+    }
+
+    # SPA fallback
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    # Static assets cache
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff2?)$ {
+        expires 30d;
+        add_header Cache-Control "public, immutable";
+    }
+}