fix: resolve CS1574 unresolved DatabaseFacade/ChangeTracker doc crefs in sample DbContexts (#539) (#549)

Adds the missing using Microsoft.EntityFrameworkCore.Infrastructure (and
.ChangeTracking where needed) directives so XML doc <see cref=.../> tags
referencing DatabaseFacade.EnsureCreated(Async) and ChangeTracker.Clear
resolve correctly, matching the existing pattern in TodoApp.Avalonia.

Affected sample DbContexts:
- TodoApp.Uno/Database/AppDbContext.cs
- TodoApp.WPF/Database/AppDbContext.cs
- TodoApp.WinUI3/Database/AppDbContext.cs
- TodoApp.BlazorWasm.Server/Database/TodoContext.cs

Co-authored-by: ahall <ahall@cloudflare.com>

Author: adrianhall

samples/todoapp-blazor-wasm/TodoApp.BlazorWasm.Server/Database/TodoContext.cs

@@ -3,6 +3,8 @@
 // See the LICENSE file in the project root for more information.
 
 using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.ChangeTracking;
+using Microsoft.EntityFrameworkCore.Infrastructure;
 
 namespace TodoApp.BlazorWasm.Server.Database;
 

samples/todoapp/TodoApp.Uno/TodoApp.Uno/Database/AppDbContext.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
 
 namespace TodoApp.Uno.Database;
 

samples/todoapp/TodoApp.WPF/Database/AppDbContext.cs

@@ -7,6 +7,7 @@
 using CommunityToolkit.Datasync.Client.Http;
 using CommunityToolkit.Datasync.Client.Offline;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
 using TodoApp.WPF.Services;
 
 namespace TodoApp.WPF.Database;

samples/todoapp/TodoApp.WinUI3/Database/AppDbContext.cs

@@ -7,6 +7,7 @@
 using CommunityToolkit.Datasync.Client.Http;
 using CommunityToolkit.Datasync.Client.Offline;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
 using System;
 using System.Linq;
 using System.Threading;