Release v4.3: speak status line (Tolk) + Logging tab with housekeeping

- New screen-reader hotkey "Speak the RemSound status information" (issue #13):
  reads the status line aloud through the active screen reader via Tolk, fires from
  anywhere (system-wide), unset by default. Built behind an IScreenReaderOutput seam
  so a future build can swap Tolk for Prism on Windows 10+ without touching callers.
  Tolk DLLs vendored under tolk/ and shipped next to the exe.
- New Logging tab in Preferences: Enable logs + Write logs now moved there, plus
  opt-in startup "warn if logs folder exceeds N MB" and "delete logs older than N days",
  and a "Delete all logs" button (Yes/No confirm). New LogMaintenance helper + AppConfig
  settings drive it.
- Manual (readme.html + regenerated MANUAL.md), About changelog and RELEASE_NOTES
  updated in plain English; csproj <Version> bumped to 4.3.

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

src/RemSound.App/ScreenReader.cs

@@ -0,0 +1,45 @@
+namespace RemSound.App;
+
+/// <summary>
+/// Process-wide screen-reader speech. Used for feedback the screen reader can't otherwise observe —
+/// chiefly the "speak the status line" hotkey (GitHub issue #13), which must read aloud even when the
+/// global hotkey fires while RemSound isn't the focused window.
+///
+/// Holds a single backend, created once on first use. Today that is always Tolk, which works on every
+/// Windows version RemSound supports — including Windows 7. The interface seam exists so a future build
+/// can choose a different backend per OS without changing any caller: branch inside
+/// <see cref="CreateBackend"/>. (Prism is the modern successor to Tolk but requires Windows 10+, so it
+/// can't be the default while Win7 is supported — see <see cref="IScreenReaderOutput"/>.)
+/// </summary>
+internal static class ScreenReader
+{
+    private static readonly object sync = new();
+    private static IScreenReaderOutput? backend;
+
+    private static IScreenReaderOutput Backend
+    {
+        get { lock (sync) { return backend ??= CreateBackend(); } }
+    }
+
+    private static IScreenReaderOutput CreateBackend()
+    {
+        // Win7-safe default. To adopt Prism on Windows 10+ later, branch on Environment.OSVersion
+        // here and return a PrismScreenReaderOutput when the OS is >= Windows 10 — callers below stay
+        // exactly as they are.
+        return new TolkScreenReaderOutput();
+    }
+
+    /// <summary>Speak text through the active screen reader (best-effort; silent if none is running).
+    /// Returns true if it reached a screen reader.</summary>
+    public static bool Speak(string text, bool interrupt = true) => Backend.Speak(text, interrupt);
+
+    /// <summary>Release the backend on app shutdown. Safe to call when nothing was ever spoken.</summary>
+    public static void Shutdown()
+    {
+        lock (sync)
+        {
+            backend?.Shutdown();
+            backend = null;
+        }
+    }
+}