Add video preview, source crop, find-videos, and render toasts

Bring the Video tab closer to Shorts with 4K preview stills and crop
modes (none, auto, center, plus the visual editor). Settings store a
default source folder so Find videos can collect output.avi sequences.
Cap the FFmpeg log with auto-scroll, hide repeat spam, and show a
Windows notification when a video or short finishes or fails.

Package.appxmanifest

@@ -5,7 +5,9 @@
   xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
   xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
   xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
-  IgnorableNamespaces="uap rescap">
+  xmlns:com="http://schemas.microsoft.com/appx/manifest/com/windows10"
+  xmlns:desktop="http://schemas.microsoft.com/appx/manifest/desktop/windows10"
+  IgnorableNamespaces="uap rescap com desktop">
 
   <Identity
     Name="F004AE73-5989-46F3-B913-E9A3A355713F"
@@ -42,6 +44,18 @@
         <uap:DefaultTile Wide310x150Logo="Assets\Wide310x150Logo.png" />
         <uap:SplashScreen Image="Assets\SplashScreen.png" BackgroundColor="#0E1525" />
       </uap:VisualElements>
+      <Extensions>
+        <desktop:Extension Category="windows.toastNotificationActivation">
+          <desktop:ToastNotificationActivation ToastActivatorCLSID="F004AE73-5989-46F3-B913-E9A3A3557140" />
+        </desktop:Extension>
+        <com:Extension Category="windows.comServer">
+          <com:ComServer>
+            <com:ExeServer Executable="AmiReel.exe" DisplayName="AmiReel" Arguments="----AppNotificationActivated:">
+              <com:Class Id="F004AE73-5989-46F3-B913-E9A3A3557140" />
+            </com:ExeServer>
+          </com:ComServer>
+        </com:Extension>
+      </Extensions>
     </Application>
   </Applications>