Add PII redaction POC for secure LLM prompting.

Implements detect-redact-sanitize pipeline with regex, domain rules, and ONNX NER before the LLM boundary, plus NUnit tests and Xenovex push documentation.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/PiiRedaction.Infrastructure.Tests/Onnx/RealNerModelRunnerTests.cs

@@ -0,0 +1,51 @@
+using FluentAssertions;
+
+using PiiRedaction.Core.Models;
+
+using PiiRedaction.Tests.Shared;
+
+
+
+namespace PiiRedaction.Infrastructure.Tests.Onnx;
+
+
+
+[TestFixture]
+
+[Category("RealModel")]
+
+public sealed class RealNerModelRunnerTests : RealNerModelFixture
+
+{
+
+    [TestCase("Customer Ravi Kumar called about billing.", "Ravi", "Ravi Kumar")]
+
+    [TestCase("Mr. John Smith called about a duplicate debit.", "John", "John Smith")]
+
+    public void PredictEntities_DetectsPersonWithCorrectSpan(string prompt, string expectedNamePart, string expectedValue)
+
+    {
+
+        var entities = Runner.PredictEntities(prompt);
+
+
+
+        entities.Should().Contain(entity =>
+
+            entity.Type == PiiEntityType.Person &&
+
+            entity.Source == PiiDetectionSource.Ner &&
+
+            entity.Value.Contains(expectedNamePart, StringComparison.Ordinal) &&
+
+            prompt.AsSpan(entity.StartIndex, entity.Length).ToString() == entity.Value);
+
+
+
+        entities.Should().Contain(entity => entity.Value == expectedValue);
+
+    }
+
+}
+
+