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.

OSGKeyboardShared/Models/FlowUtteranceChunkConfig.swift

@@ -1,7 +1,7 @@
 // FlowUtteranceChunkConfig.swift
 // OSGKeyboard · Shared
 //
-// Chunking policy for pipelined Flow utterance ASR (up to 3 minutes).
+// Chunking policy for pipelined Flow utterance ASR (up to 3.5 minutes).
 
 import Foundation
 

OSGKeyboardShared/Models/HandednessPreference.swift

@@ -0,0 +1,29 @@
+// HandednessPreference.swift
+// OSGKeyboard · Shared
+//
+// Which hand the user holds the phone with — controls bottom-row key order
+// on the keyboard (delete ↔ return swap for right-handed use).
+
+import Foundation
+
+public enum HandednessPreference: String, CaseIterable, Identifiable, Sendable, Codable {
+    case left
+    case right
+
+    public var id: String { rawValue }
+
+    public var labelKey: String {
+        switch self {
+        case .left:  return "settings.handedness.left"
+        case .right: return "settings.handedness.right"
+        }
+    }
+
+    /// Right-handed preference places return on the left and delete on the right.
+    public var swapsActionKeys: Bool { self == .right }
+
+    public static func fromStored(_ raw: String?) -> HandednessPreference {
+        guard let raw, let value = HandednessPreference(rawValue: raw) else { return .left }
+        return value
+    }
+}

OSGKeyboardShared/Models/ProviderConfig.swift

@@ -52,6 +52,7 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
         // "on" state during init, but new writes never touch the key.
         static let translationTargetLocaleId = "config.translationTargetLocaleId"
         static let polishScenarioId = "config.polishScenarioId"
+        static let handednessPreference = "config.handednessPreference"
     }
 
     @Published public var providerId: String {
@@ -163,6 +164,14 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
             AppGroupConfigDarwin.postConfigChanged()
         }
     }
+    /// Which hand the user holds the phone with — mirrors to the keyboard
+    /// extension so delete / return can swap on the bottom row.
+    @Published public var handednessPreference: HandednessPreference {
+        didSet {
+            defaults.set(handednessPreference.rawValue, forKey: Key.handednessPreference)
+            AppGroupConfigDarwin.postConfigChanged()
+        }
+    }
 
     /// Whether the pipeline should run translate-and-polish (not just
     /// polish). Cloud engine: any selected target locale. Local engine:
@@ -299,6 +308,9 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
                 self.polishScenarioId = PolishScenarioCatalog.defaultId
             }
         }
+        self.handednessPreference = HandednessPreference.fromStored(
+            resolvedDefaults.string(forKey: Key.handednessPreference)
+        )
 
         // Cloud no longer exposes off/transcribe; migrate legacy values.
         if self.engineMode == "cloud", self.modeId != "polish" {
@@ -350,6 +362,7 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
         model = preset.defaultModel
         systemPrompt = AppGroupStore.defaultSystemPrompt(for: "openai")
         polishScenarioId = PolishScenarioCatalog.defaultId
+        handednessPreference = .left
         hasAcknowledgedCloudSharing = false
     }
 }