refactor(flow): remove Live Activity and keep-alive mode picker

Keep voice sessions on silent low-profile PiP only, and fix custom polish style editor presentation via sheet(item:).

OSGKeyboardExt/Services/KeyboardFlowCoordinator.swift

@@ -122,7 +122,6 @@ final class KeyboardFlowCoordinator {
     /// prepares PiP so the next press does not need another app switch.
     func ensurePiPReadyOnKeyboardOpen() {
         guard FlowHandoffPolicy.allowsProactiveHostAutoLaunch,
-              FlowSessionPolicy.keepAliveMode() == .pictureInPicture,
               state.hasCompletedOnboarding,
               hasFullAccess(),
               AppGroup.isAvailable,
@@ -220,7 +219,7 @@ final class KeyboardFlowCoordinator {
         // host utt.rec=1 → ready=false → keyboard forever "正在启动…".
         let hostBusy = FlowKeyboardHostWarming.isHostBusy(reason: readySnapshot?.reason)
         // Hold green after the session already proved ready — PiP mic release /
-        // ack lag must not flash yellow「正在启动画中画».
+        // ack lag must not flash yellow「正在启动…」.
         let holdReady = FlowKeyboardHostWarming.shouldHoldReady(
             hostReady: hostReadyRaw,
             hostBusy: hostBusy,

OSGKeyboardExt/en.lproj/Keyboard.strings

@@ -134,12 +134,10 @@
 
 /* Flow session (keyboard) */
 "keyboard.flow.sessionInactive" = "Voice session off";
-"keyboard.flow.sessionInactive.pip" = "Picture in Picture off — tap mic to open OSGKeyboard";
 "keyboard.flow.start" = "Start";
 "keyboard.flow.startA11y" = "Start voice session";
 "keyboard.flow.sessionExpired" = "Voice session ended. Open OSGKeyboard to restart.";
 "keyboard.flow.startingSession" = "Starting voice session…";
-"keyboard.flow.startingSession.pip" = "Starting Picture in Picture…";
 "keyboard.flow.transcribing" = "Transcribing…";
 "keyboard.flow.resultTimeout" = "Timed out waiting for transcription. Try again.";
 "keyboard.flow.hostDisconnected" = "Voice session disconnected. Open OSGKeyboard to restart.";

OSGKeyboardExt/zh-Hans.lproj/Keyboard.strings

@@ -134,12 +134,10 @@
 
 /* Flow session (keyboard) */
 "keyboard.flow.sessionInactive" = "语音会话未启动";
-"keyboard.flow.sessionInactive.pip" = "画中画未启动，点麦克风打开 OSGKeyboard";
 "keyboard.flow.start" = "启动";
 "keyboard.flow.startA11y" = "启动语音会话";
 "keyboard.flow.sessionExpired" = "语音会话已结束，请打开 OSGKeyboard 重新启动";
 "keyboard.flow.startingSession" = "正在启动语音会话…";
-"keyboard.flow.startingSession.pip" = "正在启动画中画…";
 "keyboard.flow.transcribing" = "识别中…";
 "keyboard.flow.resultTimeout" = "等待识别结果超时，请重试";
 "keyboard.flow.hostDisconnected" = "语音会话已断开，请打开 OSGKeyboard 重新启动";