Add project files.

LearningChineseSimplified/Pages/Counter.razor

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+@page "/counter"
+
+<PageTitle>Counter</PageTitle>
+
+<MudText Typo="Typo.h3" GutterBottom="true">Counter</MudText>
+<MudText Class="mb-4">Current count: @currentCount</MudText>
+<MudButton Color="Color.Primary" Variant="Variant.Filled" @onclick="IncrementCount">Click me</MudButton>
+
+
+@code {
+    private int currentCount = 0;
+
+    private void IncrementCount()
+    {
+        currentCount++;
+    }
+}