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/Sources/VoiceCatCore/VoiceCatClient.swift

@@ -417,6 +417,15 @@ public final class VoiceCatClient {
         VoiceCatResult(vc_set_input_gain(handle, gain < 0 ? 0 : gain))
     }
 
+    /// Send-side microphone noise suppression (RNNoise). Denoises captured MIC PCM before the
+    /// input gain and VAD/PTT gate, so everyone hears the cleaned signal (one pass for all
+    /// listeners). MIC stream only, mono only; always LOCAL — no protocol traffic. Independent
+    /// of the per-listener receive-side NR in `setRemoteStream` (docs/voice.md §10).
+    @discardableResult
+    public func setInputNoiseReduction(_ enable: Bool) -> VoiceCatResult {
+        VoiceCatResult(vc_set_input_noise_reduction(handle, enable ? 1 : 0))
+    }
+
     // MARK: - AVAudioSession interruption hooks (iOS)
 
     /// Pause miniaudio device I/O. Call when AVAudioSession interruption begins.

clients/apple/iOS/VoiceCatiOS/SessionState.swift

@@ -27,6 +27,7 @@ struct VoiceState {
     var inputMode: VoiceCatInputMode = .voiceActivation
     var vadThreshold: Float = 0.025
     var inputGain: Float = 1.0
+    var inputNoiseReduction: Bool = false
     var level: Float = 0.0
     var currentDeviceId: String?
     var localStreamId: UInt32 = 0
@@ -353,12 +354,19 @@ final class SessionState {
         UserDefaults.standard.set(gain, forKey: DefaultsKey.inputGain)
     }
 
+    func setInputNoiseReduction(_ on: Bool) {
+        client.setInputNoiseReduction(on)
+        voiceState.inputNoiseReduction = on
+        UserDefaults.standard.set(on, forKey: DefaultsKey.inputNoiseReduction)
+    }
+
     // MARK: - Persisted input settings
 
     private enum DefaultsKey {
         static let inputMode    = "voice.inputMode"
         static let vadThreshold = "voice.vadThreshold"
         static let inputGain    = "voice.inputGain"
+        static let inputNoiseReduction = "voice.inputNoiseReduction"
     }
 
     /// Restore the saved input mode / VAD threshold / mic gain and push them into the core so a
@@ -375,9 +383,13 @@ final class SessionState {
         if d.object(forKey: DefaultsKey.inputGain) != nil {
             voiceState.inputGain = d.float(forKey: DefaultsKey.inputGain)
         }
+        if d.object(forKey: DefaultsKey.inputNoiseReduction) != nil {
+            voiceState.inputNoiseReduction = d.bool(forKey: DefaultsKey.inputNoiseReduction)
+        }
         client.setInputMode(voiceState.inputMode)
         client.setVadThreshold(voiceState.vadThreshold)
         client.setInputGain(voiceState.inputGain)
+        client.setInputNoiseReduction(voiceState.inputNoiseReduction)
     }
 
     private var pttEngaged = false

clients/apple/iOS/VoiceCatiOS/Views/SettingsView.swift

@@ -251,6 +251,13 @@ struct SettingsView: View {
                         .accessibilityLabel("Microphone volume")
                         .accessibilityValue("\(Int((session.voiceState.inputGain * 100).rounded())) percent")
                     }
+
+                    Toggle("Noise Reduction (RNNoise)", isOn: Binding(
+                        get: { session.voiceState.inputNoiseReduction },
+                        set: { session.setInputNoiseReduction($0) }
+                    ))
+                    .accessibilityLabel("Microphone noise reduction")
+                    .accessibilityHint("Denoises your microphone signal for everyone listening.")
                 }
 
                 // MARK: - Notifications

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)

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

@@ -58,6 +58,11 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
     }()
     private let inputGainValueLabel = NSTextField(labelWithString: "100%")
 
+    // Send-side mic noise reduction (RNNoise). MIC-only. Persisted via
+    // MainWindowController.inputNoiseReduction.
+    private let nrCheckbox = NSButton(checkboxWithTitle: "Noise reduction (RNNoise)",
+                                       target: nil, action: nil)
+
     // Aux input stream: a second outgoing stream from another hardware input device (e.g. line-in
     // / aux), captured client-side. Device + volume only — aux is always-on. Persisted via
     // MainWindowController.auxEnabled / auxDeviceUID / auxGain.
@@ -168,6 +173,11 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
         inputGainSlider.setAccessibilityHelp("Boost a quiet microphone. 100% is unity.")
         inputGainValueLabel.setAccessibilityLabel("Microphone volume value")
 
+        nrCheckbox.target = self
+        nrCheckbox.action = #selector(nrChanged)
+        nrCheckbox.setAccessibilityLabel("Microphone noise reduction")
+        nrCheckbox.setAccessibilityHelp("RNNoise denoising of your microphone. Cleans your signal for everyone.")
+
         let inputModeRow = NSStackView(views: [inputModeLabel, inputModeControl])
         inputModeRow.orientation = .horizontal
         inputModeRow.spacing = 8
@@ -249,7 +259,7 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
         volumeRow.orientation = .horizontal
         volumeRow.spacing = 8
 
-        let stack = NSStackView(views: [inputModeRow, vadRow, inputGainRow, pttRow, deviceRow,
+        let stack = NSStackView(views: [inputModeRow, vadRow, inputGainRow, nrCheckbox, pttRow, deviceRow,
                                         levelRow, auxHeader, auxCheckbox, auxDeviceRow, auxGainRow,
                                         notificationsHeader, soundsCheckbox, volumeRow,
                                         speechCheckbox, selfTalkCheckbox, pttSoundCheckbox])
@@ -319,6 +329,7 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
 
         inputGainSlider.doubleValue = Double(mc.inputGain * 100)
         updateInputGainLabel()
+        nrCheckbox.state = mc.inputNoiseReduction ? .on : .off
 
         auxCheckbox.state = mc.auxEnabled ? .on : .off
         auxGainSlider.doubleValue = Double(mc.auxGain * 100)
@@ -371,6 +382,14 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
         }
     }
 
+    @objc private func nrChanged() {
+        let on = nrCheckbox.state == .on
+        mainController?.inputNoiseReduction = on
+        if let mc = mainController, mc.micStreamId != 0 {
+            client.setInputNoiseReduction(on)
+        }
+    }
+
     private func updateInputGainLabel() {
         let pct = Int(inputGainSlider.doubleValue.rounded())
         inputGainValueLabel.stringValue = "\(pct)%"