chore(sonar): bulk-fix mechanical CA/IDE analyzer warnings

Applied via `dotnet format analyzers --diagnostics IDE0028 CA1825 CA1834
CA1845 CA1847 CA1860 CA1866 CA1853 CA1830 CA1846 CA1806 CA1869 CA2249
--severity info`. 19 files touched, all mechanical syntactic rewrites:

- CA1847: string.Contains("x") -> string.Contains('x')
- CA2249: s.IndexOf(c) == -1 -> !s.Contains(c)
- CA1830: sb.Append(sb.ToString()) -> sb.Append(sb)
- CA1834: StringBuilder.Append("x") -> Append('x')
- CA1825, CA1860, CA1866, CA1853, IDE0028, CA1845: corresponding fixers

Three rules in the batch had no batch fixer available (CA1846 ×4,
CA1806 ×1, CA1869 ×1) and stay open for separate manual handling.

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

tests/Strata.SqlTools.PostgreSql.Tests/PostgreSql/QueryBreakdownTests.cs

@@ -513,7 +513,7 @@ public class QueryBreakdownTests
 
         // Assert
         // Find the UserId parameter value
-        var userIdKey = merged.Keys.FirstOrDefault(k => k.Contains("UserId") && !k.Contains("$"));
+        var userIdKey = merged.Keys.FirstOrDefault(k => k.Contains("UserId") && !k.Contains('$'));
         Assert.That(userIdKey, Is.Not.Null);
         Assert.That(merged[userIdKey], Is.EqualTo(123)); // Main query value, not CTE value
     }
@@ -559,9 +559,9 @@ public class QueryBreakdownTests
         var merged = mainQuery.GetMergedParameters();
 
         // Assert
-        var dateKey = merged.Keys.FirstOrDefault(k => k.Contains("CreatedDate") && !k.Contains("$"));
-        var boolKey = merged.Keys.FirstOrDefault(k => k.Contains("IsActive") && !k.Contains("$"));
-        var doubleKey = merged.Keys.FirstOrDefault(k => k.Contains("Threshold") && !k.Contains("$"));
+        var dateKey = merged.Keys.FirstOrDefault(k => k.Contains("CreatedDate") && !k.Contains('$'));
+        var boolKey = merged.Keys.FirstOrDefault(k => k.Contains("IsActive") && !k.Contains('$'));
+        var doubleKey = merged.Keys.FirstOrDefault(k => k.Contains("Threshold") && !k.Contains('$'));
 
         Assert.That(dateKey, Is.Not.Null);
         Assert.That(merged[dateKey], Is.TypeOf<DateTime>());

tests/Strata.SqlTools.Rules.Tests/RuleVisitorTests.cs

@@ -133,7 +133,7 @@ public class TestRuleInput
 
     public string? ImGoingToMakeThisNull { get; set; } = null;
 
-    public TestRuleDetail[] Details { get; set; } = { };
+    public TestRuleDetail[] Details { get; set; } = Array.Empty<TestRuleDetail>();
 }
 
 public class TestRuleDetail

tests/Strata.SqlTools.SqlBreakdown.Tests/ExpressionTests/ExpressionFactoryFilterTests.cs

@@ -31,7 +31,7 @@ public class ExpressionFactoryFilterTests : ExpressionTestsBase
         ).SetName("CalendarFilter_{m}");
 
         yield return new TestCaseData(
-            new Filter(4, FilterType.Timeframe, new object[] { }, Array.Empty<FilterCondition>(), DatePart.Month, false, 1, 3),
+            new Filter(4, FilterType.Timeframe, Array.Empty<object>(), Array.Empty<FilterCondition>(), DatePart.Month, false, 1, 3),
             $"DEPT.DISCHARGE_DATE >= '{startOfCurrentMonth:yyyy-MM-dd}' AND DEPT.DISCHARGE_DATE < '{startOfEndMonth:yyyy-MM-dd}'"
         ).SetName("TimeframeFilter_{m}");
     }

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

@@ -174,7 +174,7 @@ public class RecursiveCTETests
         var merged = mainQuery.GetMergedParameters();
 
         // Assert
-        var statusKey = merged.Keys.FirstOrDefault(k => k.Contains("Status") && !k.Contains("@") && !k.Contains("$"));
+        var statusKey = merged.Keys.FirstOrDefault(k => k.Contains("Status") && !k.Contains('@') && !k.Contains('$'));
         Assert.That(statusKey, Is.Not.Null);
         Assert.That(merged[statusKey], Is.EqualTo("active"), "Main query parameter should take precedence");
     }