add client chat page & chat overlay window

lib/pages/file_manager_page.dart

@@ -0,0 +1,38 @@
+import 'dart:io';
+import 'package:file_manager/file_manager.dart';
+import 'package:flutter/material.dart';
+
+final FileManagerController controller = FileManagerController();
+
+class FileManagerPage extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+        body: FileManager(
+      controller: controller,
+      builder: (context, snapshot) {
+        final List<FileSystemEntity> entities = snapshot;
+        return ListView.builder(
+          itemCount: entities.length,
+          itemBuilder: (context, index) {
+            return Card(
+              child: ListTile(
+                leading: FileManager.isFile(entities[index])
+                    ? Icon(Icons.feed_outlined)
+                    : Icon(Icons.folder),
+                title: Text(FileManager.basename(entities[index])),
+                onTap: () {
+                  if (FileManager.isDirectory(entities[index])) {
+                    controller.openDirectory(entities[index]); // open directory
+                  } else {
+                    // Perform file-related tasks.
+                  }
+                },
+              ),
+            );
+          },
+        );
+      },
+    ));
+  }
+}