redesigned payment page + a lot of fixes

frontend/pweb/lib/pages/report/operations/states/error.dart

@@ -0,0 +1,31 @@
+import 'package:flutter/material.dart';
+
+
+class OperationHistoryError extends StatelessWidget {
+  final String message;
+  final String retryLabel;
+  final VoidCallback onRetry;
+
+  const OperationHistoryError({
+    super.key,
+    required this.message,
+    required this.retryLabel,
+    required this.onRetry,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Column(
+        mainAxisAlignment: MainAxisAlignment.center,
+        children: [
+          Text(message),
+          ElevatedButton(
+            onPressed: onRetry,
+            child: Text(retryLabel),
+          ),
+        ],
+      ),
+    );
+  }
+}

frontend/pweb/lib/pages/report/operations/states/loading.dart

@@ -0,0 +1,11 @@
+import 'package:flutter/material.dart';
+
+
+class OperationHistoryLoading extends StatelessWidget {
+  const OperationHistoryLoading({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Center(child: CircularProgressIndicator());
+  }
+}