Remove the demo text-parsing domain

The scaffolding domain existed to prove the shell end to end before there was
anything real to put in it. There is now, so it goes - as CLAUDE.md promised it
would.

Gone: the two sample parsers, ITextParser, ParsedRecord, the parser catalog,
ParseViewModel and ParseView, their tests, and the settings key that remembered
which parser was last used. ParseError.LineNumber becomes Index, since for a
listing "line 42" was simply untrue, and the error keys move from Parse.Error.*
to Collect.Error.* now that parsing is not a concept here.

Kept: IParser<,>, ParseOutcome, ParseProgress and ParseError. The streaming
contract was always the general part - it was only ever the text-shaped closure
of it that was scaffolding.

Rendering the dashboard caught two keys that were referenced but never added
during the rename: the XAML was repointed and the resources were not. The parity
test could not see it, because it compares the two files against each other and
a key absent from both is consistent. That gap now has its own test, which reads
every {l:Loc} in the XAML and checks it resolves - a screenshot is too late and
too manual a way to find a missing string.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/AvParser.UI/DependencyInjection/UiServiceCollectionExtensions.cs

@@ -1,5 +1,4 @@
 using AvParser.Core.Collecting;
-using AvParser.Core.Parsing;
 using AvParser.Core.Proxies;
 using AvParser.Core.Settings;
 using AvParser.Infrastructure.Proxies;
@@ -32,13 +31,6 @@ public static class UiServiceCollectionExtensions
         services.AddSingleton<INavigationService, NavigationService>();
 
         services.AddSingleton<DashboardViewModel>();
-        services.AddSingleton<ParseViewModel>(static sp => new ParseViewModel(
-            sp.GetRequiredService<IParserCatalog>(),
-            sp.GetRequiredService<ISettingsService>(),
-            sp.GetRequiredService<IProxyPool>(),
-            sp,
-            sp.GetRequiredService<ILogger<ParseViewModel>>()
-        ));
         services.AddSingleton<SettingsViewModel>(static sp => new SettingsViewModel(
             sp.GetRequiredService<ISettingsService>(),
             sp.GetRequiredService<IThemeService>(),
@@ -66,7 +58,6 @@ public static class UiServiceCollectionExtensions
 
         // Order here is the order of the navigation rail; the first entry is the landing page.
         services.AddSingleton<PageViewModel>(static sp => sp.GetRequiredService<DashboardViewModel>());
-        services.AddSingleton<PageViewModel>(static sp => sp.GetRequiredService<ParseViewModel>());
         services.AddSingleton<PageViewModel>(static sp => sp.GetRequiredService<CollectViewModel>());
         services.AddSingleton<PageViewModel>(static sp => sp.GetRequiredService<ProxiesViewModel>());
         services.AddSingleton<PageViewModel>(static sp => sp.GetRequiredService<SettingsViewModel>());