Release v3.5: USB-card recovery, per-card adaptive buffer, one user folder, audit fixes

- Recover an unplugged/replugged output sound card automatically (issue #5):
  detect the dead WASAPI device and remember the receive-output selection so it
  re-ticks and re-opens when the card returns.
- Adaptive per-card WASAPI buffer target sized to each card's pull chunk, held
  stable so it never flits about under CPU/network load.
- Consolidate all per-user data (config, profiles, logs, sounds) into one
  "user settings and logs" folder; migrate every older layout; exclude it from
  the updater so custom cue sounds now survive updates.
- Mic-privacy detector: warn once when a Windows-blocked mic is switched on, or a
  profile loads with one already on.
- All warning/notice dialogs now come to the foreground even when minimised.
- Apply volume + mute on profile load (were saved but not restored).
- Crash-safe (atomic) profile/config saves.
- Fix two resource leaks (push-mode capture MMDevice; UPnP DeviceFound handler).
- Remove dead code (baseline-diff machinery, dead ASIO probes, no-op stubs).
- Docs: readme.html, MANUAL.md, About-box changelog and release notes for v3.5.

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

src/RemSound.App/RouterPortMapper.cs

@@ -130,6 +130,11 @@ internal sealed class RouterPortMapper : IDisposable
         RaiseChanged();
         try
         {
+            // Subscribe-once: Refresh() (fired on every sleep/wake) calls Start() again without a
+            // prior unsubscribe, and DeviceFound is a STATIC Mono.Nat event — a bare += would stack
+            // a new handler every resume (duplicate port-maps + this object kept alive forever).
+            // Remove first so there's only ever one subscription.
+            NatUtility.DeviceFound -= OnDeviceFound;
             NatUtility.DeviceFound += OnDeviceFound;
             NatUtility.StartDiscovery();
             log?.Invoke("UPnP discovery started");