diag(ios,audio): log AVAudioSession state + route changes around picker overrides

Add structured NSLog instrumentation to AppDelegate.swift and debugPrint
chains in voice_compact.dart::_AudioOutputPickerSheetState so we can
correlate user picker taps with what iOS actually does to the route.

Three diagnostic streams:

* 'chanora.session[<tag>]' from Swift — full session snapshot (category,
  mode, sampleRate, ioBufferDuration, current route inputs+outputs,
  preferredInput) emitted on every setActive and every
  AVAudioSession.routeChangeNotification with the reason decoded
  (override / routeConfigurationChange / newDeviceAvailable / etc).
* 'chanora.route[<tag>]' from Dart — current route's inputs+outputs
  emitted before/after every overrideOutputAudioPort or
  setPreferredInput call, plus a delayed re-check at +250 ms to detect
  silent reverts.
* Existing 'chanora: ...' debugPrint lines from the picker now include
  the OK case (override returned, setPreferredInput returned) so we see
  a positive signal in the log when the API didn't throw.

Used to root-cause the 'speaker selector not working' issue: the
hypothesis is that cpal's RemoteIO AudioUnit reacts to its own format
configuration notifications by triggering routeConfigurationChange
that reverts our Dart-side override. The logs will confirm or deny
this — if we see 'chanora.session[routeChange.override] out=Speaker'
followed by 'chanora.session[routeChange.routeConfigurationChange]
out=Receiver' within a few hundred ms, that's the smoking gun.

Pure diagnostic commit. No behavioural change. Logs are NSLog +
debugPrint so they appear in Xcode console / 'flutter logs' / the
device log via Console.app or 'devicectl device log'.

apps/chanora_flutter/lib/widgets/voice_compact.dart

@@ -766,65 +766,78 @@ class _AudioOutputPickerSheetState extends State<_AudioOutputPickerSheet> {
     }
   }
 
+  /// Diagnostic helper: log the current route's first input and
+  /// output ports with a tag so we can correlate user actions with
+  /// what iOS thinks the route is. Called immediately before an
+  /// override, immediately after, and again 250 ms later to detect
+  /// silent revert.
+  Future<void> _logRoute(String tag) async {
+    try {
+      final route = await AVAudioSession().currentRoute;
+      final outs = route.outputs
+          .map((o) => '${o.portType.name}/${o.portName}')
+          .join(',');
+      final ins = route.inputs
+          .map((i) => '${i.portType.name}/${i.portName}')
+          .join(',');
+      debugPrint('chanora.route[$tag] out=[$outs] in=[$ins]');
+    } catch (e) {
+      debugPrint('chanora.route[$tag] FAILED: $e');
+    }
+  }
+
   Future<void> _selectSpeaker() async {
+    await _logRoute('speaker.before');
     try {
-      // Apple-documented quirk: in .voiceChat mode, calling
-      // setPreferredInput(builtInMic) AFTER overrideOutputAudioPort(.speaker)
-      // causes iOS to recalculate the route. Built-in mic naturally
-      // pairs with the receiver (not the speaker), so the system
-      // SILENTLY REVERTS the speaker override and routes audio
-      // back through the earpiece. Net: the await chain returns
-      // successfully ('no exception'), but the user hears no
-      // change.
-      //
-      // Fix: do NOT call setPreferredInput when forcing speaker.
-      // The speaker override is sufficient on its own \u2014 input
-      // remains on whatever the system was already using (built-in
-      // mic by default, or BT/wired if connected and selected
-      // elsewhere). For consistency, only switch input when the
-      // user explicitly picks a non-speaker input row.
       await AVAudioSession()
           .overrideOutputAudioPort(AVAudioSessionPortOverride.speaker);
-      debugPrint('chanora: audio output -> speakerphone (override applied)');
+      debugPrint('chanora: override(.speaker) returned OK');
     } catch (e, st) {
       debugPrint('chanora: _selectSpeaker FAILED: $e\n$st');
     }
+    await _logRoute('speaker.after');
+    // Schedule a delayed re-check — if cpal's RemoteIO unit reverts
+    // the route on routeChangeNotification, this will surface the
+    // revert (out=builtInReceiver instead of builtInSpeaker).
+    Future.delayed(const Duration(milliseconds: 250), () {
+      _logRoute('speaker.after+250ms');
+    });
     if (!mounted) return;
     Navigator.of(context).pop();
   }
 
   Future<void> _selectReceiver() async {
+    await _logRoute('receiver.before');
     try {
-      // Same quirk in reverse: removing the speaker override
-      // (.none) is enough to restore the .voiceChat default route,
-      // which is the built-in receiver. Calling setPreferredInput
-      // explicitly here is redundant and risks the same recalc
-      // race that broke _selectSpeaker before.
       await AVAudioSession()
           .overrideOutputAudioPort(AVAudioSessionPortOverride.none);
-      debugPrint('chanora: audio output -> receiver (override cleared)');
+      debugPrint('chanora: override(.none) returned OK');
     } catch (e, st) {
       debugPrint('chanora: _selectReceiver FAILED: $e\n$st');
     }
+    await _logRoute('receiver.after');
+    Future.delayed(const Duration(milliseconds: 250), () {
+      _logRoute('receiver.after+250ms');
+    });
     if (!mounted) return;
     Navigator.of(context).pop();
   }
 
   Future<void> _selectInput(AVAudioSessionPortDescription port) async {
+    await _logRoute('input.${port.portType.name}.before');
     try {
-      // Drop any speakerphone override so the route follows the
-      // selected input. BT / wired headset / USB inputs pair their
-      // OWN output (the user hears audio through the same device
-      // they speak into), so .none + setPreferredInput is the
-      // correct combo here.
       await AVAudioSession()
           .overrideOutputAudioPort(AVAudioSessionPortOverride.none);
       await AVAudioSession().setPreferredInput(port);
       debugPrint(
-          'chanora: audio output -> ${port.portName} (${port.portType})');
+          'chanora: setPreferredInput(${port.portName}/${port.portType.name}) OK');
     } catch (e, st) {
       debugPrint('chanora: _selectInput FAILED: $e\n$st');
     }
+    await _logRoute('input.${port.portType.name}.after');
+    Future.delayed(const Duration(milliseconds: 250), () {
+      _logRoute('input.${port.portType.name}.after+250ms');
+    });
     if (!mounted) return;
     Navigator.of(context).pop();
   }