Add chapter 12 blazor project

Chapter12/Complete/BlazorTasksWasm/Pages/Counter.razor

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+@page "/counter"
+
+<PageTitle>Counter</PageTitle>
+
+<h1>Counter</h1>
+
+<p role="status">Current count: @currentCount</p>
+
+<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>
+
+@code {
+    private int currentCount = 0;
+
+    private void IncrementCount()
+    {
+        currentCount++;
+    }
+}

Chapter12/Complete/BlazorTasksWasm/Pages/FetchData.razor

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+@page "/fetchdata"
+@inject HttpClient Http
+
+<PageTitle>Weather forecast</PageTitle>
+
+<h1>Weather forecast</h1>
+
+<p>This component demonstrates fetching data from the server.</p>
+
+@if (forecasts == null)
+{
+    <p><em>Loading...</em></p>
+}
+else
+{
+    <table class="table">
+        <thead>
+            <tr>
+                <th>Date</th>
+                <th>Temp. (C)</th>
+                <th>Temp. (F)</th>
+                <th>Summary</th>
+            </tr>
+        </thead>
+        <tbody>
+            @foreach (var forecast in forecasts)
+            {
+                <tr>
+                    <td>@forecast.Date.ToShortDateString()</td>
+                    <td>@forecast.TemperatureC</td>
+                    <td>@forecast.TemperatureF</td>
+                    <td>@forecast.Summary</td>
+                </tr>
+            }
+        </tbody>
+    </table>
+}
+
+@code {
+    private WeatherForecast[]? forecasts;
+
+    protected override async Task OnInitializedAsync()
+    {
+        forecasts = await Http.GetFromJsonAsync<WeatherForecast[]>("sample-data/weather.json");
+    }
+
+    public class WeatherForecast
+    {
+        public DateOnly Date { get; set; }
+
+        public int TemperatureC { get; set; }
+
+        public string? Summary { get; set; }
+
+        public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
+    }
+}

Chapter12/Complete/BlazorTasksWasm/Pages/Index.razor

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+@page "/"
+
+<PageTitle>Index</PageTitle>
+
+<h1>Hello, world!</h1>
+
+Welcome to your new app.
+
+<SurveyPrompt Title="How is Blazor working for you?" />

Chapter12/Complete/BlazorTasksWasm/Pages/Tasks.razor

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+@page "/tasks"
+<h3>Tasks - (@taskList.Count(task => !task.IsComplete)) incomplete</h3>
+<ul>
+    @foreach (var task in taskList)
+    {
+        <li>
+            <input type="checkbox" @bind="task.IsComplete" />
+            <input @bind="task.Name" />
+        </li>
+    }
+</ul>
+<input placeholder="Enter new task..." @bind="newTask" />
+<button @onclick="AddTask">Add task</button>
+@code {
+    private IList<TaskItem> taskList = new List<TaskItem>();
+    private string? newTask;
+    private void AddTask()
+    {
+        if (!string.IsNullOrWhiteSpace(newTask))
+        {
+            taskList.Add(new TaskItem { Name = newTask });
+            newTask = string.Empty;
+        }
+    }
+}