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.

scripts/tamil-ner-diagnostic/Program.cs

@@ -0,0 +1,27 @@
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using Microsoft.ML.Tokenizers;
+using PiiRedaction.Core.Configuration;
+using PiiRedaction.Infrastructure.Onnx;
+
+var modelDir = Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "..", "..", "models", "ta"));
+if (!Directory.Exists(modelDir))
+{
+    modelDir = Path.GetFullPath("models/ta");
+}
+
+var vocabPath = Path.Combine(modelDir, "vocab.txt");
+var bertOptions = new BertOptions { LowerCaseBeforeTokenization = false, ApplyBasicTokenization = false };
+var tokenizer = BertTokenizer.Create(vocabPath, bertOptions);
+var text = "வாடிக்கையாளர் ராஜேஷ் குமார் அழைத்தார்.";
+var tokens = tokenizer.EncodeToTokens(text, out _, considerPreTokenization: true, considerNormalization: true);
+Console.WriteLine($"count={tokens.Count}");
+foreach (var t in tokens) Console.WriteLine($"{t.Id}\t{t.Value}");
+
+var runnerOptions = Options.Create(new PiiRedactionOptions { TamilOnnxModelPath = Path.Combine(modelDir, "model.onnx") });
+using var runner = new TamilOnnxNerRunner(runnerOptions, NullLogger<TamilOnnxNerRunner>.Instance);
+Console.WriteLine($"Available: {runner.IsModelAvailable}");
+foreach (var e in runner.PredictEntities(text))
+{
+    Console.WriteLine($"Entity: '{e.Value}' [{e.StartIndex},{e.Length}]");
+}