init: EasyScreen 电子菜单系统

- server: FastAPI 后端（多屏管理、素材上传、节目编排、客户端注册/配置/心跳/崩溃上报、管理台托管）
- android: Java 客户端（minSdk 23，全屏图片/视频轮播、远程配置、开机自启、崩溃上报）
- web: React + Vite + antd 管理台（屏幕/素材/节目管理）
- 屏幕设备 ID 关联机制、gunicorn 生产部署脚本

server/settings.json

@@ -0,0 +1,40 @@
+{
+  "active_db": "dev_sqlite",
+  "databases": {
+    "dev_sqlite": {
+      "type": "sqlite",
+      "path": "./easyscreen.db"
+    },
+    "dev": {
+      "type": "mysql",
+      "host": "127.0.0.1",
+      "port": 3306,
+      "user": "easyscreen",
+      "password": "",
+      "database_name": "easyscreen",
+      "charset": "utf8mb4"
+    },
+    "production": {
+      "type": "mysql",
+      "host": "你的MySQL内网地址",
+      "port": 3306,
+      "user": "easyscreen",
+      "password": "",
+      "database_name": "easyscreen",
+      "charset": "utf8mb4"
+    }
+  },
+  "server": {
+    "host": "0.0.0.0",
+    "port": 5889,
+    "base_url": "http://192.168.1.100:5889",
+    "upload_dir": "./uploads",
+    "max_upload_mb": 500,
+    "allowed_types": ["image/jpeg", "image/png", "image/gif", "image/webp", "video/mp4", "video/webm", "video/x-matroska"]
+  },
+  "admin": {
+    "username": "admin",
+    "password": "admin123",
+    "token_secret": "请修改为随机字符串"
+  }
+}