feat: add AngleDisplay MVVM UserControl for advance monitoring

Refactors the old AngleDisplay code-behind into a clean MVVM implementation
with AngleDisplayViewModel (PSG/INJ/Manual encoder angles, zero references,
lock angle calculation with tolerance color coding) and a pure XAML view.
Wires LockAngleFaseReady and PsgModeFaseReady test phase events.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Views/UserControls/AngleDisplayView.xaml.cs

@@ -0,0 +1,16 @@
+using System.Windows.Controls;
+
+namespace HC_APTBS.Views.UserControls
+{
+    /// <summary>
+    /// Advance monitoring display for PSG, Injector, and Manual encoder angles.
+    /// All logic resides in <see cref="ViewModels.AngleDisplayViewModel"/>.
+    /// </summary>
+    public partial class AngleDisplayView : UserControl
+    {
+        public AngleDisplayView()
+        {
+            InitializeComponent();
+        }
+    }
+}