Surface NER routing provenance (ModelOrigin, NerModelsInvoked) through the pipeline and WPF harness so English/Tamil routing is observable during POC validation. Consolidate docs into solution-guide and add NER logs, topic filtering, and batch UI fixes in the test harness.

scripts/tamil-ner-diagnostic/Program.cs

@@ -21,7 +21,7 @@ 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))
+foreach (var e in runner.PredictEntities(text).Entities)
 {
     Console.WriteLine($"Entity: '{e.Value}' [{e.StartIndex},{e.Length}]");
 }