chore: rename miniplayer.json to miniplayer.ui

Sources/MiniPlayerApp.swift

@@ -139,8 +139,8 @@ struct BricksAppView: View {
     }
     
     private func loadJSONString() -> String {
-        // 从 Resources 加载 miniplayer.json
-        if let url = Bundle.module.url(forResource: "miniplayer", withExtension: "json"),
+        // 从 Resources 加载 miniplayer.ui
+        if let url = Bundle.module.url(forResource: "miniplayer", withExtension: "ui"),
            let data = try? Data(contentsOf: url),
            let str = String(data: data, encoding: .utf8) {
             return str