feat: keyboard bottom-row layout, handedness preference, and screen wake lock

Rework the action cluster to a mic-above-bottom-row layout, add left/right
handedness setting that swaps delete and return, and keep the screen awake
during Flow recording sessions.

OSGKeyboard/Services/FlowSessionManager.swift

@@ -140,6 +140,7 @@ final class FlowSessionManager: ObservableObject {
         FlowSessionBridge.writeHeartbeat()
         FlowSessionDarwin.postSessionChanged()
         isActive = true
+        ScreenWakeLock.acquire()
         if let expires = FlowSessionBridge.sessionExpiresAt() {
             sessionExpiresAt = Date(timeIntervalSince1970: expires)
         }
@@ -187,6 +188,7 @@ final class FlowSessionManager: ObservableObject {
 
         capture.stop()
         endBackgroundKeepAlive()
+        ScreenWakeLock.release()
         sessionASR = nil
         FlowSessionBridge.markSessionInactive()
         FlowSessionDarwin.postSessionChanged()
@@ -321,6 +323,7 @@ final class FlowSessionManager: ObservableObject {
         FlowSessionBridge.markSessionActive(duration: duration)
         FlowSessionDarwin.postSessionChanged()
         isActive = true
+        ScreenWakeLock.acquire()
         sessionExpiresAt = Date().addingTimeInterval(duration)
 
         startHeartbeat()

OSGKeyboard/Utilities/ScreenWakeLock.swift

@@ -0,0 +1,26 @@
+// ScreenWakeLock.swift
+// OSGKeyboard · Main App
+//
+// Reference-counted idle-timer disable for Flow session ownership.
+
+import UIKit
+
+@MainActor
+enum ScreenWakeLock {
+    private static var holdCount = 0
+
+    static func acquire() {
+        holdCount += 1
+        if holdCount == 1 {
+            UIApplication.shared.isIdleTimerDisabled = true
+        }
+    }
+
+    static func release() {
+        guard holdCount > 0 else { return }
+        holdCount -= 1
+        if holdCount == 0 {
+            UIApplication.shared.isIdleTimerDisabled = false
+        }
+    }
+}

OSGKeyboard/Views/SettingsView.swift

@@ -78,6 +78,7 @@ struct SettingsView: View {
                                 localEngineSettingsSection
                             }
                             if presentation == .tab {
+                                preferencesSection
                                 footerLinks
                             }
                         }
@@ -253,6 +254,27 @@ struct SettingsView: View {
         dynamicLocales = entries
     }
 
+    // MARK: - Preferences (tab settings only)
+
+    private var preferencesSection: some View {
+        VStack(alignment: .leading, spacing: SettingsListMetrics.sectionLabelSpacing) {
+            sectionHeader("settings.preferences.title")
+            VStack(spacing: 0) {
+                HandednessPickerRow(
+                    selection: Binding(
+                        get: { config.handednessPreference },
+                        set: { config.handednessPreference = $0 }
+                    )
+                )
+            }
+            .background(palette.surface, in: RoundedRectangle(cornerRadius: Radius.xl, style: .continuous))
+            .overlay(
+                RoundedRectangle(cornerRadius: Radius.xl, style: .continuous)
+                    .stroke(palette.divider, lineWidth: 0.5)
+            )
+        }
+    }
+
     // MARK: - Footer links (tab settings only)
 
     private var footerLinks: some View {
@@ -366,6 +388,31 @@ struct SettingsView: View {
     }
 }
 
+// MARK: - Handedness picker row
+
+private struct HandednessPickerRow: View {
+    @Binding var selection: HandednessPreference
+
+    private var options: [(id: String, label: String)] {
+        HandednessPreference.allCases.map { preference in
+            (preference.rawValue, AppL10n.string(preference.labelKey))
+        }
+    }
+
+    var body: some View {
+        PickerRow(
+            title: AppL10n.string("settings.handedness.title"),
+            options: options,
+            selection: Binding(
+                get: { selection.rawValue },
+                set: { newValue in
+                    selection = HandednessPreference(rawValue: newValue) ?? .left
+                }
+            )
+        )
+    }
+}
+
 // MARK: - Picker row (generic)
 
 private struct PickerRow: View {

OSGKeyboard/en.lproj/Localizable.strings

@@ -135,6 +135,10 @@
 "settings.systemPrompt.edit" = "Edit system prompt";
 "settings.systemPrompt.hint" = "Used by the cloud LLM when polishing your dictation. Local engine skips this step.";
 "settings.about.title" = "About";
+"settings.preferences.title" = "Preferences";
+"settings.handedness.title" = "Handedness";
+"settings.handedness.left" = "Left hand";
+"settings.handedness.right" = "Right hand";
 "settings.systemPrompt.reset" = "Reset";
 "settings.asrLocale" = "ASR locale";
 "settings.engineBadge.ios26" = "SpeechAnalyzer — always on-device";

OSGKeyboard/zh-Hans.lproj/Localizable.strings

@@ -135,6 +135,10 @@
 "settings.systemPrompt.edit" = "编辑系统提示";
 "settings.systemPrompt.hint" = "云端润色时使用。本地识别模式不会用到此提示词。";
 "settings.about.title" = "关于";
+"settings.preferences.title" = "偏好设置";
+"settings.handedness.title" = "握持偏好";
+"settings.handedness.left" = "左手";
+"settings.handedness.right" = "右手";
 "settings.systemPrompt.reset" = "重置";
 "settings.asrLocale" = "识别语言";
 "settings.engineBadge.ios26" = "SpeechAnalyzer — 始终端侧";