refactor(tests): migrate Database.Tests from FluentAssertions to Shouldly

Replace FluentAssertions with Shouldly across all 6 test files (94 tests).
Add ShouldlyExtensions for BeCloseTo and BeEquivalentTo patterns.

NEW/tests/JdeScoping.Database.Tests/Infrastructure/ShouldlyExtensions.cs

@@ -0,0 +1,45 @@
+using Shouldly;
+
+namespace JdeScoping.Database.Tests.Infrastructure;
+
+/// <summary>
+/// Extension methods for Shouldly to support patterns from FluentAssertions.
+/// </summary>
+public static class ShouldlyExtensions
+{
+    /// <summary>
+    /// Asserts that a nullable DateTime is close to the expected value within a tolerance.
+    /// Equivalent to FluentAssertions' BeCloseTo.
+    /// </summary>
+    public static void ShouldBeCloseTo(this DateTime? actual, DateTime expected, TimeSpan tolerance)
+    {
+        actual.ShouldNotBeNull();
+        Math.Abs((actual.Value - expected).TotalMilliseconds)
+            .ShouldBeLessThanOrEqualTo(tolerance.TotalMilliseconds);
+    }
+
+    /// <summary>
+    /// Asserts that a DateTime is close to the expected value within a tolerance.
+    /// Equivalent to FluentAssertions' BeCloseTo.
+    /// </summary>
+    public static void ShouldBeCloseTo(this DateTime actual, DateTime expected, TimeSpan tolerance)
+    {
+        Math.Abs((actual - expected).TotalMilliseconds)
+            .ShouldBeLessThanOrEqualTo(tolerance.TotalMilliseconds);
+    }
+
+    /// <summary>
+    /// Asserts that two collections contain equivalent items (same items, order independent).
+    /// Equivalent to FluentAssertions' BeEquivalentTo for simple types.
+    /// </summary>
+    public static void ShouldBeEquivalentTo<T>(this IEnumerable<T> actual, IEnumerable<T> expected)
+    {
+        var actualList = actual.ToList();
+        var expectedList = expected.ToList();
+        actualList.Count.ShouldBe(expectedList.Count, "Collections should have the same count");
+        foreach (var item in expectedList)
+        {
+            actualList.ShouldContain(item);
+        }
+    }
+}