Gear cleanup + Default Location for Recordings + single Start + socials hover glow

KISS: removed Gear-menu Save/SaveAs/Open Layout (redundant with auto-save; multi-layout = OBS).
App Settings: first real setting — Default Location for Recordings (Browse + Use Downloads reset,
fallback: configured → Downloads → MyVideos). Single Start button (pills = intent, button = trigger).
Socials button moved to preview bottom row, left of TRAX; hover pulses the SocialBarElement
DropShadowEffect (sine wave BlurRadius 24→48, Opacity 0.7→1.0 at 30ms). TextBox OneWay binding
fix for get-only RecordFolderDisplay. ONE fallback test. Build 0 warnings, 247 tests (2 known).

MainWindow.xaml.cs

@@ -7,6 +7,8 @@ using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Media;
+using System.Windows.Media.Effects;
+using System.Windows.Threading;
 using System.Windows.Media.Animation;
 using System.Windows.Media.Imaging;
 using System.Windows.Shapes;
@@ -560,6 +562,54 @@ public partial class MainWindow : Window
         e.Handled = true;
     }
 
+    private DispatcherTimer? _socialGlowTimer;
+    private double _socialGlowAngle;
+
+    private void SocialsButton_MouseEnter(object sender, MouseEventArgs e)
+    {
+        if (SocialBarElement == null) return;
+
+        // Kick the social bar to full brightness so it's immediately visible
+        var effect = SocialBarElement.Effect as DropShadowEffect;
+        if (effect != null)
+        {
+            effect.BlurRadius = 40;
+            effect.Opacity = 1.0;
+        }
+
+        // Pulse the glow so it catches the eye
+        _socialGlowAngle = 0;
+        _socialGlowTimer?.Stop();
+        _socialGlowTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(30) };
+        _socialGlowTimer.Tick += SocialGlowTick;
+        _socialGlowTimer.Start();
+    }
+
+    private void SocialsButton_MouseLeave(object sender, MouseEventArgs e)
+    {
+        _socialGlowTimer?.Stop();
+        _socialGlowTimer = null;
+
+        if (SocialBarElement?.Effect is DropShadowEffect effect)
+        {
+            effect.BlurRadius = 18;
+            effect.Opacity = 0.9;
+        }
+    }
+
+    private void SocialGlowTick(object? sender, EventArgs e)
+    {
+        if (SocialBarElement?.Effect is not DropShadowEffect effect) return;
+
+        _socialGlowAngle += 0.18;
+        if (_socialGlowAngle > Math.PI * 2) _socialGlowAngle -= Math.PI * 2;
+
+        // Smooth sine pulse: BlurRadius 24→48, Opacity 0.7→1.0
+        double t = (Math.Sin(_socialGlowAngle) + 1.0) / 2.0; // 0..1
+        effect.BlurRadius = 24 + t * 24;
+        effect.Opacity = 0.7 + t * 0.3;
+    }
+
     private void Preview_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
     {
         if (!_viewModel.IsEditMode) return;