feat(clients): wire RNNoise mic noise reduction into Windows, macOS, and iOS

Expose the existing send-side vc_set_input_noise_reduction C ABI (MIC-only,
mono, LOCAL — denoises captured mic PCM before input gain and VAD/PTT gate)
as a persisted global toggle in each client's audio settings, applied live
and re-applied on Join Voice. Mirrors the existing mic-gain wiring pattern.

- Shared Swift (VoiceCatCore): add setInputNoiseReduction(_:) wrapper
- Windows: P/Invoke + SetInputNoiseReduction wrapper, MicNoiseReduction in
  VoiceSettings, new checkbox in AudioSettingsForm (layout shifted +28px),
  apply on Join Voice; also fix stale 'planned - currently passthrough'
  label on the receive-side per-user NR checkbox (RNNoise now backs it)
- macOS: inputNoiseReduction state + UserDefaults in MainWindowController,
  NR checkbox + nrChanged action in SettingsWindowController
- iOS: inputNoiseReduction in VoiceState + setter + restore in SessionState,
  NR Toggle in SettingsView Voice section

Aux/screen are out of scope by design (core's NR guards kind == MIC). Apple
builds require a rebuilt VoiceCatCore.xcframework with VOICECAT_HAS_NS.

clients/apple/macOS/VoiceCatMac/Windows/MainWindowController.swift

@@ -61,6 +61,7 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
         static let inputMode    = "voice.inputMode"
         static let vadThreshold = "voice.vadThreshold"
         static let inputGain    = "voice.inputGain"
+        static let inputNoiseReduction = "voice.inputNoiseReduction"
         static let pttKeyCode   = "voice.pttKeyCode"
         static let auxEnabled   = "voice.auxEnabled"
         static let auxDeviceUID = "voice.auxDeviceUID"
@@ -76,6 +77,9 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
     internal var inputGain: Float = 1.0 {
         didSet { UserDefaults.standard.set(inputGain, forKey: AudioDefaults.inputGain) }
     }
+    internal var inputNoiseReduction: Bool = false {
+        didSet { UserDefaults.standard.set(inputNoiseReduction, forKey: AudioDefaults.inputNoiseReduction) }
+    }
     internal var selectedInputDeviceId: String?
 
     // Aux outgoing stream: a second hardware input device the client captures itself and feeds to
@@ -156,6 +160,9 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
         if d.object(forKey: AudioDefaults.inputGain) != nil {
             inputGain = d.float(forKey: AudioDefaults.inputGain)
         }
+        if d.object(forKey: AudioDefaults.inputNoiseReduction) != nil {
+            inputNoiseReduction = d.bool(forKey: AudioDefaults.inputNoiseReduction)
+        }
         if d.object(forKey: AudioDefaults.pttKeyCode) != nil {
             pttKeyCode = UInt16(d.integer(forKey: AudioDefaults.pttKeyCode))
         }
@@ -779,6 +786,7 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
                     client.setVadThreshold(vadThresholdValue)
                 }
                 client.setInputGain(inputGain)
+                client.setInputNoiseReduction(inputNoiseReduction)
                 setVoiceJoinedState(true)
                 addActivity("Joined voice — microphone active")
                 EventFeedback.shared.play(.voiceOn)