接入自建后端 + Gitea CI/CD

- 新增 server/：Node + Express + SQLite + node-cron 实现登录、纪念日 CRUD 和定时订阅消息推送
- 新增 .gitea/workflows/deploy.yml：推送即触发群晖 Docker 部署，监听 15002
- utils/api.js：自动按 envVersion 切换本地/线上 BASE_URL
- app.js 与 add-anniversary.js 移除 wx.cloud 调用，改走自建后端
- cloudfunctions/ 暂保留以便回滚
- 一并提交此前未入库的首页 / 设置页 / 日历 / 万年历等改造

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/docker-compose.yml

@@ -0,0 +1,18 @@
+services:
+  birthday-server:
+    build:
+      context: .
+      args:
+        HTTP_PROXY: http://host.docker.internal:29758
+        HTTPS_PROXY: http://host.docker.internal:29758
+        NO_PROXY: localhost,127.0.0.1
+    container_name: birthday-server
+    restart: unless-stopped
+    ports:
+      - "3000:3000"
+    env_file:
+      - .env
+    volumes:
+      - ./data:/app/data
+    environment:
+      - TZ=Asia/Shanghai