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).

ytLive.Tests/LayoutStorePersistenceTests.cs

@@ -4,6 +4,7 @@ using Microsoft.Data.Sqlite;
 using Xunit;
 using ytLive.Models;
 using ytLive.Services;
+using ytLive.ViewModels;
 
 namespace ytLive.Tests;
 
@@ -389,6 +390,8 @@ public class LayoutStorePersistenceTests
         }
     }
 
+    // TASK 21: media-source config (Path, Looping, Volume, PlaybackState) must
+    // survive a save + reload through the full DELETE-all/re-insert cycle.
     // TASK 21: media-source config (Path, Looping, Volume, PlaybackState) must
     // survive a save + reload through the full DELETE-all/re-insert cycle.
     [Fact]
@@ -431,4 +434,19 @@ public class LayoutStorePersistenceTests
             try { File.Delete(path); } catch { /* best-effort cleanup */ }
         }
     }
+
+    // TASK: default record folder falls back to Downloads (0th case / no preference).
+    [Fact]
+    public void DefaultRecordFolder_Falls_Back_To_Downloads()
+    {
+        var folder = MainViewModel.DefaultRecordFolder();
+        var downloads = Path.Combine(
+            Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "Downloads");
+
+        if (Directory.Exists(downloads))
+            Assert.Equal(downloads, folder);
+        else
+            Assert.Equal(
+                Environment.GetFolderPath(Environment.SpecialFolder.MyVideos), folder);
+    }
 }