fix(installer): release the ShellLink COM object so reading a .lnk doesn't lock it

src/ClaudeDo.Installer/Core/ShortcutFactory.cs

@@ -8,24 +8,36 @@ public static class ShortcutFactory
 {
     private const int SlgpRawPath = 0x4;
 
+    // Both helpers release the ShellLink RCW explicitly. IPersistFile.Load/Save keeps a handle on
+    // the .lnk for as long as the COM object lives, so leaving it to the GC lets a read immediately
+    // followed by a write to the same path fail with "used by another process" — exactly what
+    // AutostartShortcut.Install does when the recorded target changed.
     public static void CreateShortcut(string shortcutPath, string targetPath, string workingDir, string description)
     {
         var link = (IShellLink)new ShellLink();
-        link.SetPath(targetPath);
-        link.SetWorkingDirectory(workingDir);
-        link.SetDescription(description);
-        link.SetIconLocation(targetPath, 0);
+        try
+        {
+            link.SetPath(targetPath);
+            link.SetWorkingDirectory(workingDir);
+            link.SetDescription(description);
+            link.SetIconLocation(targetPath, 0);
 
-        var file = (IPersistFile)link;
-        file.Save(shortcutPath, false);
+            var file = (IPersistFile)link;
+            file.Save(shortcutPath, false);
+        }
+        finally
+        {
+            Marshal.FinalReleaseComObject(link);
+        }
     }
 
     /// <summary>Reads the target path of an existing .lnk, or null if it can't be read (missing/corrupt).</summary>
     public static string? TryGetTarget(string shortcutPath)
     {
+        IShellLink? link = null;
         try
         {
-            var link = (IShellLink)new ShellLink();
+            link = (IShellLink)new ShellLink();
             ((IPersistFile)link).Load(shortcutPath, 0);
             var sb = new StringBuilder(260);
             link.GetPath(sb, sb.Capacity, IntPtr.Zero, SlgpRawPath);
@@ -36,6 +48,10 @@ public static class ShortcutFactory
         {
             return null;
         }
+        finally
+        {
+            if (link is not null) Marshal.FinalReleaseComObject(link);
+        }
     }
 
     [ComImport]