v4.1: two screen-reader fixes — silent start-in-tray, announce on restore

- Starting straight into the tray (StartMinimised / --minimized) no longer plays the "minimise"
  cue; only a genuine user minimise does (the startup path passes playCue:false)
- Restoring the window from the tray now lands focus on a real named control on the active tab so
  NVDA announces it, instead of resting on the role-less QuietTabControl and surfacing silently
- Shared the focus-a-leaf-for-announcement helper between the main window and Preferences

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/RemSound.App/AboutDialog.cs

@@ -20,6 +20,17 @@ internal sealed class AboutDialog : Form
     /// updates" path.</summary>
     private const string ReleaseNotes =
         """
+        RemSound v4.1
+
+        A couple of small fixes for screen-reader users. When
+        RemSound starts straight into the notification area, it no
+        longer plays the "minimise" sound — starting in the tray
+        isn't the same as you choosing to hide the window, so it
+        shouldn't sound the cue. And when you bring the window back
+        from the tray, RemSound now lands on a control on whichever
+        tab you'd left open, so your screen reader announces the
+        window instead of coming up silent.
+
         RemSound v4.0
 
         RemSound now has a sound for nearly everything you do.