refactor: address code review findings across all projects

Apply comprehensive fixes from code reviews including:
- Extract shared utilities (SqlFormatHelper, CellValueConverter, DbDestinationBase)
- Add interface abstractions (IAuthenticationService, IDatabaseMigrator, IMisQueryBuilder)
- Implement SecureStore for encrypted secrets storage
- Fix error handling with proper HTTP status codes and logging
- Optimize double enumeration in DevEtlRegistry
- Add DataSync.Dev README for developer onboarding
- Extract filter panel base classes to reduce duplication
- Update code review docs to mark all issues as fixed

NEW/src/Utils/JdeScoping.SecureStoreManager/ViewModels/ViewModelBase.cs

@@ -0,0 +1,39 @@
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace JdeScoping.SecureStoreManager.ViewModels;
+
+/// <summary>
+/// Base class for all view models providing INotifyPropertyChanged implementation.
+/// </summary>
+public abstract class ViewModelBase : INotifyPropertyChanged
+{
+    public event PropertyChangedEventHandler? PropertyChanged;
+
+    /// <summary>
+    /// Raises the PropertyChanged event for the specified property.
+    /// </summary>
+    /// <param name="propertyName">The name of the property that changed.</param>
+    protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
+    {
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+    }
+
+    /// <summary>
+    /// Sets a property value and raises PropertyChanged if the value changed.
+    /// </summary>
+    /// <typeparam name="T">The type of the property.</typeparam>
+    /// <param name="field">Reference to the backing field.</param>
+    /// <param name="value">The new value.</param>
+    /// <param name="propertyName">The name of the property.</param>
+    /// <returns>True if the value changed, false otherwise.</returns>
+    protected bool SetProperty<T>(ref T field, T value, [CallerMemberName] string? propertyName = null)
+    {
+        if (EqualityComparer<T>.Default.Equals(field, value))
+            return false;
+
+        field = value;
+        OnPropertyChanged(propertyName);
+        return true;
+    }
+}