feat: 添加 Docker 部署配置

- 添加 Dockerfile (多阶段构建: Node 构建 → Nginx 托管)
- 添加 docker-compose.yml (端口 8801, 自动重启)
- 添加 .dockerignore (减少构建体积)
- 添加 docker-deploy.md (部署文档)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,43 @@
+# Node.js
+node_modules
+npm-debug.log
+yarn-error.log
+
+# Build outputs
+dist
+build
+
+# Git
+.git
+.gitignore
+.gitattributes
+
+# IDE
+.vscode
+.idea
+*.swp
+*.swo
+
+# Documentation
+README.md
+PRD.md
+*.md
+!docker-deploy.md
+
+# Docker
+Dockerfile
+docker-compose.yml
+.dockerignore
+
+# Environment
+.env
+.env.local
+.env.*.local
+
+# Test
+coverage
+.nyc_output
+
+# Misc
+.DS_Store
+Thumbs.db