feat: 初始化屏幕播放控制系统

搭建基于 Flask 的多屏幕定时播放控制后端，提供设备管理控制台、播放端页面、媒体上传与配置文件持久化，并补充项目文档、示例配置及 MIT 许可证。

config.json

@@ -0,0 +1,38 @@
+{
+    "devices": [
+        {
+            "id": "d1",
+            "name": "主屏幕",
+            "playlist": [
+                {
+                    "type": "image",
+                    "path": "/static/image1.png",
+                    "start_time": "2024-11-21T16:32:10",
+                    "duration": 10
+                },
+                {
+                    "type": "video",
+                    "path": "/static/video1.mp4",
+                    "start_time": "2024-11-21T16:55:00"
+                }
+            ]
+        },
+        {
+            "id": "d2",
+            "name": "副屏幕",
+            "playlist": [
+                {
+                    "type": "image",
+                    "path": "/static/image1.png",
+                    "start_time": "2024-11-21T16:26:10",
+                    "duration": 10
+                },
+                {
+                    "type": "video",
+                    "path": "/static/video2.mp4",
+                    "start_time": "2024-11-21T16:40:00"
+                }
+            ]
+        }
+    ]
+}