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/Services/AppGroupStore.swift

@@ -46,6 +46,7 @@ public struct AppGroupStore: @unchecked Sendable {
         // computed shim for source compatibility.
         static let translationTargetLocaleId = "config.translationTargetLocaleId"
         static let polishScenarioId = "config.polishScenarioId"
+        static let handednessPreference = "config.handednessPreference"
     }
 
     // MARK: - Reads
@@ -133,6 +134,11 @@ public struct AppGroupStore: @unchecked Sendable {
         return PolishScenarioCatalog.resolve(stored ?? PolishScenarioCatalog.defaultId).id
     }
 
+    /// Bottom-row key order on the keyboard extension.
+    public var handednessPreference: HandednessPreference {
+        HandednessPreference.fromStored(defaults.string(forKey: Key.handednessPreference))
+    }
+
     // MARK: - Writes
 
     public func setModeId(_ id: String) {
@@ -184,6 +190,11 @@ public struct AppGroupStore: @unchecked Sendable {
         AppGroupConfigDarwin.postConfigChanged()
     }
 
+    public func setHandednessPreference(_ preference: HandednessPreference) {
+        defaults.set(preference.rawValue, forKey: Key.handednessPreference)
+        AppGroupConfigDarwin.postConfigChanged()
+    }
+
     /// Whether ASR output should be sent through the cloud LLM step.
     /// Cloud engine: always. Local engine: only when cloud polish is
     /// enabled (translation is a sub-option of that step).

OSGKeyboardShared/Services/FlowSessionKeys.swift

@@ -24,8 +24,8 @@ public enum FlowSessionKeys {
     /// Default Flow session length when started from the keyboard.
     public static let defaultSessionDuration: TimeInterval = 480
 
-    /// Maximum duration for a single keyboard utterance (3 minutes).
-    public static let maxUtteranceDuration: TimeInterval = 180
+    /// Maximum duration for a single keyboard utterance (3.5 minutes).
+    public static let maxUtteranceDuration: TimeInterval = 210
 
     /// Host polls for pipelined ASR drain after mic stop. Pipelining usually
     /// finishes most chunks during recording; this is a soft deadline before

OSGKeyboardShared/Services/KeyboardState.swift

@@ -103,6 +103,8 @@ public final class KeyboardState: ObservableObject {
     /// v0.2.0: mirrored from App Group — local engine runs the cloud
     /// LLM step only when this is `true`.
     @Published public var localModeCloudPolishEnabled: Bool = false
+    /// Mirrored from App Group — swaps delete / return on the bottom row.
+    @Published public var handednessPreference: HandednessPreference = .left
     /// Whether translate-and-polish is actually armed for the current
     /// engine (local requires cloud polish + a target locale).
     public var isTranslationEffective: Bool {