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.

tests/TestSupport.Shared/RealTamilNerModelFixture.cs

@@ -0,0 +1,45 @@
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using PiiRedaction.Core.Configuration;
+using PiiRedaction.Infrastructure.Onnx;
+
+namespace PiiRedaction.Tests.Shared;
+
+/// <summary>
+/// Reuses a single <see cref="TamilOnnxNerRunner"/> per fixture for performance.
+/// Skips all tests in the class when the Tamil ONNX model is missing or cannot be loaded.
+/// </summary>
+public abstract class RealTamilNerModelFixture
+{
+    protected TamilOnnxNerRunner Runner { get; private set; } = null!;
+
+    protected string ModelPath { get; private set; } = null!;
+
+    [OneTimeSetUp]
+    public void OneTimeSetUpTamilModel()
+    {
+        ModelPath = RealTamilNerModelPaths.ResolveRepoModelPath();
+        if (!File.Exists(ModelPath))
+        {
+            Assert.Ignore(RealTamilNerModelPaths.ModelMissingMessage);
+        }
+
+        var options = Options.Create(new PiiRedactionOptions
+        {
+            TamilOnnxModelPath = ModelPath
+        });
+        Runner = new TamilOnnxNerRunner(options, NullLogger<TamilOnnxNerRunner>.Instance);
+
+        if (!Runner.IsModelAvailable)
+        {
+            Runner.Dispose();
+            Assert.Ignore(RealTamilNerModelPaths.ModelMissingMessage);
+        }
+    }
+
+    [OneTimeTearDown]
+    public void OneTimeTearDownTamilModel()
+    {
+        Runner?.Dispose();
+    }
+}