Add Tamil NER routing and WPF test harness for POC validation.

Introduce dual-script ONNX NER routing (English/Tamil/mixed), Tamil console samples and integration tests, model download scripts, and a resizable WPF MVVM harness with click-to-load prompts, batch validation, and runtime-adjustable detection panels.

src/PiiRedaction.TestHarness.Wpf/App.xaml.cs

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+using System.IO;
+using System.Windows;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using PiiRedaction.TestHarness.Wpf.DependencyInjection;
+using PiiRedaction.TestHarness.Wpf.Services;
+using PiiRedaction.TestHarness.Wpf.ViewModels;
+
+namespace PiiRedaction.TestHarness.Wpf;
+
+public partial class App : Application
+{
+    private IHost? _host;
+
+    protected override async void OnStartup(StartupEventArgs e)
+    {
+        base.OnStartup(e);
+
+        _host = Host.CreateDefaultBuilder()
+            .ConfigureAppConfiguration((_, configuration) =>
+            {
+                configuration.SetBasePath(AppContext.BaseDirectory);
+                configuration.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);
+                configuration.AddEnvironmentVariables();
+            })
+            .ConfigureServices((context, services) =>
+            {
+                services.AddPiiRedactionServices(context.Configuration);
+                services.AddSingleton<ITestPromptCatalog, TestPromptCatalog>();
+                services.AddSingleton<IRedactionAppService, RedactionAppService>();
+                services.AddSingleton<IScriptAnalysisService, ScriptAnalysisService>();
+                services.AddSingleton<IModelStatusService, ModelStatusService>();
+                services.AddSingleton<MainViewModel>();
+                services.AddSingleton<MainWindow>();
+            })
+            .Build();
+
+        Directory.SetCurrentDirectory(AppContext.BaseDirectory);
+
+        await _host.StartAsync().ConfigureAwait(true);
+
+        var mainWindow = _host.Services.GetRequiredService<MainWindow>();
+        mainWindow.Show();
+    }
+
+    protected override async void OnExit(ExitEventArgs e)
+    {
+        if (_host is not null)
+        {
+            await _host.StopAsync().ConfigureAwait(true);
+            _host.Dispose();
+        }
+
+        base.OnExit(e);
+    }
+}