chore(sonar): wrap independent assertions in Assert.Multiple (NUnit2045)

Driven by `dotnet format analyzers --diagnostics NUnit2045`. The fixer
groups consecutive independent `Assert.That(...)` calls into
`Assert.Multiple(() => { ... })`, so a failing assertion no longer
short-circuits the block — every failure inside the group is reported,
which gives much better diagnostics on multi-property tests.

Audit confirmed no Assert.Throws / Assert.Fail / Assert.Catch / Assert.Pass
/ Assert.DoesNotThrow got pulled inside a Multiple block (those need to
short-circuit). All 1180 tests pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/Strata.SqlTools.SqlServer.Tests/SqlServer/RecursiveCTETests.cs

@@ -33,9 +33,12 @@ public class RecursiveCTETests
         var isRecursive = withClause.IsRecursive;
         var hasRecursiveQuery = withClause.RecursiveQuery != null;
 
-        // Assert
-        Assert.That(isRecursive, Is.True);
-        Assert.That(hasRecursiveQuery, Is.True);
+        Assert.Multiple(() =>
+        {
+            // Assert
+            Assert.That(isRecursive, Is.True);
+            Assert.That(hasRecursiveQuery, Is.True);
+        });
     }
 
     [Test]
@@ -143,10 +146,13 @@ public class RecursiveCTETests
 
         // Assert
         var keys = merged.Keys.ToList();
-        Assert.That(keys.Any(k => k.Contains("AnchorStatus")), "Should include anchor query parameters");
-        Assert.That(keys.Any(k => k.Contains("RecursiveLevel")), "Should include recursive query parameters");
-        Assert.That(keys.Any(k => k.Contains("RecursiveStatus")), "Should include recurring query parameters");
-        Assert.That(keys.Any(k => k.Contains("MainLimit")), "Should include main query parameters");
+        Assert.Multiple(() =>
+        {
+            Assert.That(keys.Any(k => k.Contains("AnchorStatus")), "Should include anchor query parameters");
+            Assert.That(keys.Any(k => k.Contains("RecursiveLevel")), "Should include recursive query parameters");
+            Assert.That(keys.Any(k => k.Contains("RecursiveStatus")), "Should include recurring query parameters");
+            Assert.That(keys.Any(k => k.Contains("MainLimit")), "Should include main query parameters");
+        });
     }
 
     [Test]
@@ -175,8 +181,11 @@ public class RecursiveCTETests
 
         // Assert
         var statusKey = merged.Keys.FirstOrDefault(k => k.Contains("Status") && !k.Contains('@') && !k.Contains('$'));
-        Assert.That(statusKey, Is.Not.Null);
-        Assert.That(merged[statusKey], Is.EqualTo("active"), "Main query parameter should take precedence");
+        Assert.Multiple(() =>
+        {
+            Assert.That(statusKey, Is.Not.Null);
+            Assert.That(merged[statusKey], Is.EqualTo("active"), "Main query parameter should take precedence");
+        });
     }
 
     #endregion