feat: complete legacy UI and playout parity migration

tests/MBN_STOCK_WEBVIEW.DbWriteSmoke.Tests/SmokeRunIdentityTests.cs

@@ -0,0 +1,33 @@
+#nullable enable
+
+using MBN_STOCK_WEBVIEW.DbWriteSmoke;
+
+namespace MBN_STOCK_WEBVIEW.DbWriteSmoke.Tests;
+
+public sealed class SmokeRunIdentityTests
+{
+    [Fact]
+    public void Create_ProducesCollisionResistantSafeBoundedPrefix()
+    {
+        var identity = SmokeRunIdentity.Create(
+            DateTimeOffset.Parse("2026-07-15T10:11:12+09:00"),
+            Guid.Parse("01234567-89ab-cdef-0123-456789abcdef"));
+
+        var value = identity.For("G_PROFIT");
+
+        Assert.Equal(
+            "MBW2607150123456789O",
+            value);
+        Assert.Equal(20, value.Length);
+        Assert.Matches("^[A-Z0-9]+$", value);
+    }
+
+    [Fact]
+    public void Create_RejectsEmptyNonceAndUnsafeSuffix()
+    {
+        Assert.Throws<ArgumentException>(() =>
+            SmokeRunIdentity.Create(DateTimeOffset.UtcNow, Guid.Empty));
+        var identity = SmokeRunIdentity.Create(DateTimeOffset.UtcNow, Guid.NewGuid());
+        Assert.Throws<ArgumentException>(() => identity.For("bad-value"));
+    }
+}