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/AboutDialog.cs

@@ -20,6 +20,31 @@ internal sealed class AboutDialog : Form
     /// updates" path.</summary>
     private const string ReleaseNotes =
         """
+        RemSound v4.3
+
+        Two additions for screen-reader users, and a
+        tidier home for logging.
+
+        You can now hear the RemSound status line on
+        demand. In the Keyboard shortcuts dialog set a
+        key for "Speak the RemSound status information",
+        and pressing it reads the whole status line aloud
+        through your screen reader — how long you've been
+        connected, your peers, whether sound is flowing,
+        and how healthy the link is — from anywhere, even
+        with RemSound in the tray. It's there for the
+        times your screen reader can't read the status
+        line itself. Unset to begin with, so you pick the
+        key.
+
+        Logging now has its own tab in Preferences, and it
+        can keep its own folder tidy: warn you at startup
+        if the logs folder grows past a size you choose,
+        automatically delete logs older than a number of
+        days you set, and a "Delete all logs" button to
+        clear them out at once. All three are off unless
+        you turn them on.
+
         RemSound v4.2
 
         Three fixes, one of them a real annoyance gone.