chore(sonar): second sweep — catch .Length, Is.Not.Empty, and newly-exposed Multiple groups (NUnit2046, NUnit2045)

Re-runs `dotnet format analyzers --diagnostics NUnit2046 NUnit2045` after
the Tier 2 Assert.Multiple wrap, which exposed:

- `Has.Length.EqualTo(n)` rewrites for `string[]`/array `.Length` checks
  (the first pass only knew about `.Count`).
- `Is.Not.Empty` rewrites for `Count, Is.GreaterThan(0)`.
- A handful of new NUnit2045 groups that became wrappable once the
  initial Multiple blocks settled the surrounding indentation.

Tests still 1180/1180 passing.

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

tests/Strata.SqlTools.LinqToSql.Tests/QueryCollectionAnalyzerTests.cs

@@ -406,7 +406,7 @@ public class QueryCollectionAnalyzerTests
         var similar = analyzer.FindSimilarQueries(0.5); // Lower threshold for testing
 
         // Assert
-        Assert.That(similar.Count, Is.GreaterThan(0));
+        Assert.That(similar, Is.Not.Empty);
     }
 
     [Test]

tests/Strata.SqlTools.LinqToSql.Tests/QueryValidatorTests.cs

@@ -550,7 +550,7 @@ public class QueryValidatorTests
 
         // Assert
         Assert.That(validator, Is.Not.Null);
-        Assert.That(validator.Issues.Count, Is.GreaterThan(0));
+        Assert.That(validator.Issues, Is.Not.Empty);
     }
 
     #endregion