feat(configmanager): add SearchFormViewModel

Implements Task 18 from phases 7-9 plan. SearchFormViewModel wraps
SearchSection model with properties for MaxResultRows, TimeoutSeconds,
and MaxConcurrentSearches. Includes full test coverage with 7 tests
verifying initialization, two-way binding, change notification, and
null argument handling.

NEW/src/Utils/JdeScoping.ConfigManager/ViewModels/Forms/SearchFormViewModel.cs

@@ -0,0 +1,69 @@
+using JdeScoping.ConfigManager.Models;
+
+namespace JdeScoping.ConfigManager.ViewModels.Forms;
+
+/// <summary>
+/// ViewModel for editing Search configuration section.
+/// </summary>
+public class SearchFormViewModel : ViewModelBase
+{
+    private readonly SearchSection _model;
+    private readonly Action _onChanged;
+
+    public SearchFormViewModel(SearchSection model, Action onChanged)
+    {
+        _model = model ?? throw new ArgumentNullException(nameof(model));
+        _onChanged = onChanged ?? throw new ArgumentNullException(nameof(onChanged));
+    }
+
+    /// <summary>
+    /// Gets or sets the maximum number of result rows returned by a search.
+    /// </summary>
+    public int MaxResultRows
+    {
+        get => _model.MaxResultRows;
+        set
+        {
+            if (_model.MaxResultRows != value)
+            {
+                _model.MaxResultRows = value;
+                OnPropertyChanged();
+                _onChanged();
+            }
+        }
+    }
+
+    /// <summary>
+    /// Gets or sets the timeout in seconds for search operations.
+    /// </summary>
+    public int TimeoutSeconds
+    {
+        get => _model.TimeoutSeconds;
+        set
+        {
+            if (_model.TimeoutSeconds != value)
+            {
+                _model.TimeoutSeconds = value;
+                OnPropertyChanged();
+                _onChanged();
+            }
+        }
+    }
+
+    /// <summary>
+    /// Gets or sets the maximum number of concurrent search operations allowed.
+    /// </summary>
+    public int MaxConcurrentSearches
+    {
+        get => _model.MaxConcurrentSearches;
+        set
+        {
+            if (_model.MaxConcurrentSearches != value)
+            {
+                _model.MaxConcurrentSearches = value;
+                OnPropertyChanged();
+                _onChanged();
+            }
+        }
+    }
+}

NEW/tests/JdeScoping.ConfigManager.Tests/ViewModels/Forms/SearchFormViewModelTests.cs

@@ -0,0 +1,108 @@
+using JdeScoping.ConfigManager.Models;
+using JdeScoping.ConfigManager.ViewModels.Forms;
+
+namespace JdeScoping.ConfigManager.Tests.ViewModels.Forms;
+
+public class SearchFormViewModelTests
+{
+    [Fact]
+    public void Constructor_InitializesFromModel()
+    {
+        // Arrange
+        var model = new SearchSection
+        {
+            MaxResultRows = 50000,
+            TimeoutSeconds = 600,
+            MaxConcurrentSearches = 10
+        };
+
+        // Act
+        var sut = new SearchFormViewModel(model, () => { });
+
+        // Assert
+        sut.MaxResultRows.ShouldBe(50000);
+        sut.TimeoutSeconds.ShouldBe(600);
+        sut.MaxConcurrentSearches.ShouldBe(10);
+    }
+
+    [Fact]
+    public void PropertyChange_UpdatesModel()
+    {
+        // Arrange
+        var model = new SearchSection { MaxResultRows = 100000 };
+        var sut = new SearchFormViewModel(model, () => { });
+
+        // Act
+        sut.MaxResultRows = 25000;
+
+        // Assert
+        model.MaxResultRows.ShouldBe(25000);
+    }
+
+    [Fact]
+    public void PropertyChange_InvokesOnChanged()
+    {
+        // Arrange
+        var model = new SearchSection();
+        var changedInvoked = false;
+        var sut = new SearchFormViewModel(model, () => changedInvoked = true);
+
+        // Act
+        sut.TimeoutSeconds = 120;
+
+        // Assert
+        changedInvoked.ShouldBeTrue();
+    }
+
+    [Fact]
+    public void PropertyChange_RaisesPropertyChanged()
+    {
+        // Arrange
+        var model = new SearchSection();
+        var sut = new SearchFormViewModel(model, () => { });
+        var propertyChangedRaised = false;
+        sut.PropertyChanged += (s, e) =>
+        {
+            if (e.PropertyName == nameof(SearchFormViewModel.MaxConcurrentSearches))
+                propertyChangedRaised = true;
+        };
+
+        // Act
+        sut.MaxConcurrentSearches = 8;
+
+        // Assert
+        propertyChangedRaised.ShouldBeTrue();
+    }
+
+    [Fact]
+    public void Constructor_ThrowsOnNullModel()
+    {
+        // Act & Assert
+        Should.Throw<ArgumentNullException>(() => new SearchFormViewModel(null!, () => { }));
+    }
+
+    [Fact]
+    public void Constructor_ThrowsOnNullCallback()
+    {
+        // Arrange
+        var model = new SearchSection();
+
+        // Act & Assert
+        Should.Throw<ArgumentNullException>(() => new SearchFormViewModel(model, null!));
+    }
+
+    [Fact]
+    public void PropertyChange_DoesNotInvokeOnChangedWhenValueUnchanged()
+    {
+        // Arrange
+        var model = new SearchSection { MaxResultRows = 50000 };
+        var changedCount = 0;
+        var sut = new SearchFormViewModel(model, () => changedCount++);
+
+        // Act - set to same value
+        sut.MaxResultRows = 50000;
+
+        // Assert
+        changedCount.ShouldBe(0);
+    }
+}