Multi-track + shaped/raw recording (per-peer split tracks) — held for next release

Recording Settings gains two per-profile toggles (Ed's request):
 * "Split recording into separate tracks" — each recording becomes a folder with one file per
   connected peer (their received audio only) plus one for your own send.
 * "Bypass pan and EQ when recording" — record the RAW audio (before pan/EQ) instead of the
   shaped audio you hear; applies to single and split.

Engine: a per-peer record tap in SessionPlayout hands each peer's block to the recorder RAW
(before pan/EQ) or SHAPED (after) per the bypass flag; PlayoutEngine propagates the tap to all
sessions (+ inherits on reconnect) and fires OnRecordBlockComplete each render; AudioReceiver
exposes SetPeerRecordTap / OnRecordBlockComplete. AudioRecorder now accepts an explicit path and
exposes ExtensionFor. RecordingController composes one AudioRecorder per track: multi-track =
a recorder per connected peer + a "me" recorder; single-track shaped = the existing mixed tap;
single-track raw (bypass) = sum each peer's raw block per render, flushed on the block boundary.

Naming (Ed's scheme, sortable): <recordings>/<yyyy-MM-dd>/ then, single-track, "<HH-mm-ss>
RemSound recording.<ext>"; multi-track, a folder "<HH-mm-ss> RemSound recording multi track/"
containing "<machine name> <HH-mm-ss>.<ext>" per peer (name or IP) and for your own send.

Known edge (noted): a peer using sender-side BothIndependent (two lanes) records both lanes to
one file in a split recording; single-track bypass sums per render in the Mixed path. Off by
default (both toggles unticked = today's behaviour). Builds clean; pending Ed's hands-on test.

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

src/RemSound.App/MainForm.cs

@@ -823,6 +823,11 @@ public sealed class MainForm : Form
             settings,
             msg => logFile.Event($"recorder: {msg}"));
         recordingController.RecordingStateChanged += UpdateStartStopRecordingMenuLabel;
+        // Supply the connected peers when a split recording starts, so it can make one track per peer.
+        recordingController.ConnectedPeersProvider = () =>
+            selectedPeerEndpoints
+                .Select(kv => (kv.Value.Address, selectedPeerLabels.GetValueOrDefault(kv.Key, kv.Value.Address.ToString())))
+                .ToList();
 
         // --- Set accessibility names ---
         // For these four controls the keyboard shortcut is included explicitly in both the