Add Windows citizen identity model

Author: mearvk

src/windows/WindowsCitizen.java

@@ -0,0 +1,9 @@
+package windows;
+
+/** Non-secret identity and accountability context attached to an operation. */
+public record WindowsCitizen(String id, String displayName) {
+    public WindowsCitizen {
+        if (id == null || id.isBlank()) throw new IllegalArgumentException("id is required");
+        if (displayName == null || displayName.isBlank()) throw new IllegalArgumentException("displayName is required");
+    }
+}