fix: use custom user data dir for updater WebView2 (#138)

The default location was in the install directory, which is not
writeable by regular users. We now store the WebView2 data directory in
our AppData/Local folder.

This is what it looked like when broken:

![image](https://github.com/user-attachments/assets/f6d241d7-9341-4c70-9e7f-b8230dc5c9d4)

Author: deansheather

App/App.csproj

@@ -17,6 +17,8 @@
         <LangVersion>preview</LangVersion>
         <!-- We have our own implementation of main with exception handling -->
         <DefineConstants>DISABLE_XAML_GENERATED_MAIN;DISABLE_XAML_GENERATED_BREAK_ON_UNHANDLED_EXCEPTION</DefineConstants>
+        <!-- Default version for debug builds, overridden during releases -->
+        <Version>0.1.0.0</Version>
 
         <AssemblyName>Coder Desktop</AssemblyName>
         <AssemblyTitle>Coder Desktop</AssemblyTitle>

App/ViewModels/UpdaterUpdateAvailableViewModel.cs

@@ -4,10 +4,12 @@
 using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
+using Coder.Desktop.App.Services;
 using CommunityToolkit.Mvvm.ComponentModel;
 using Microsoft.Extensions.Logging;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
+using Microsoft.Web.WebView2.Core;
 using NetSparkleUpdater;
 using NetSparkleUpdater.Enums;
 using NetSparkleUpdater.Events;
@@ -174,8 +176,18 @@ public async Task Changelog_Loaded(object sender, RoutedEventArgs e)
         if (sender is not WebView2 webView)
             return;
 
-        // Start the engine.
-        await webView.EnsureCoreWebView2Async();
+        // Start the engine with a custom user data folder. The default for
+        // unpackaged WinUI 3 apps is to write to a subfolder in the app's
+        // install directory, which is Program Files by default and not
+        // writeable by the user.
+        var userDataFolder = Path.Join(SettingsManagerUtils.AppSettingsDirectory(), "WebView2");
+        _logger.LogDebug("Creating WebView2 user data folder at {UserDataFolder}", userDataFolder);
+        Directory.CreateDirectory(userDataFolder);
+        var env = await CoreWebView2Environment.CreateWithOptionsAsync(
+            null,
+            userDataFolder,
+            new CoreWebView2EnvironmentOptions());
+        await webView.EnsureCoreWebView2Async(env);
 
         // Disable unwanted features.
         var settings = webView.CoreWebView2.Settings;