style(control-center): 모드 선택 pill로 교체하고 패널 바디로 재배치

맥락:
- Quick Controls 헤더의 모드 토글이 대시보드형 느낌을 만들어 감성 톤을 해치고 있었습니다.

변경사항:
- Control Center 헤더에서는 모드 조작 UI를 제거하고 Plan Pill + 닫기만 유지했습니다.
- 패널 바디 첫 섹션에 기본/몰입 segmented pill을 배치하고, 선택 상태에 따라 저자극 스타일을 적용했습니다.
- 모드 설명 1줄(기본: 모든 컨트롤 표시, 몰입: 필수만 남기고 숨김)을 추가했습니다.
- 모드 상태를 workspace -> tools-dock -> focus-hud 경로로 연결해 HUD 톤 반영을 유지했습니다.

검증:
- npx tsc --noEmit

세션-상태: Quick Controls 헤더가 깔끔해지고 모드 선택이 패널 바디에서 동작합니다.
세션-다음: Scene 추천 매핑 품질 점검과 override UX 검증을 진행합니다.
세션-리스크: 모드 설명 문구의 톤/길이는 실제 사용성 테스트에서 추가 미세조정이 필요할 수 있습니다.

src/widgets/control-center-sheet/ui/ControlCenterSheetWidget.tsx

@@ -16,9 +16,11 @@ interface ControlCenterSheetWidgetProps {
   rooms: RoomTheme[];
   selectedRoomId: string;
   selectedTimerLabel: string;
+  isImmersionMode: boolean;
   sceneRecommendedSoundLabel: string;
   sceneRecommendedTimerLabel: string;
   timerPresets: TimerPreset[];
+  onImmersionModeChange: (next: boolean) => void;
   onSelectRoom: (roomId: string) => void;
   onSelectTimer: (timerLabel: string) => void;
   onLockedClick: (source: string) => void;
@@ -47,9 +49,11 @@ export const ControlCenterSheetWidget = ({
   rooms,
   selectedRoomId,
   selectedTimerLabel,
+  isImmersionMode,
   sceneRecommendedSoundLabel,
   sceneRecommendedTimerLabel,
   timerPresets,
+  onImmersionModeChange,
   onSelectRoom,
   onSelectTimer,
   onLockedClick,
@@ -70,6 +74,41 @@ export const ControlCenterSheetWidget = ({
 
   return (
     <div className="space-y-4">
+      <section className="space-y-2 rounded-2xl border border-white/12 bg-black/22 p-3 backdrop-blur-md">
+        <div className="flex items-center justify-between gap-2">
+          <p className="text-[11px] text-white/64">모드</p>
+          <div className="inline-flex items-center rounded-full border border-white/14 bg-white/[0.03] p-0.5">
+            <button
+              type="button"
+              onClick={() => onImmersionModeChange(false)}
+              className={cn(
+                'h-7 rounded-full border px-3 text-[11px] transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-sky-200/70',
+                !isImmersionMode
+                  ? 'border-white/15 bg-white/10 text-white/90'
+                  : 'border-white/10 bg-transparent text-white/60 hover:text-white/78',
+              )}
+            >
+              기본
+            </button>
+            <button
+              type="button"
+              onClick={() => onImmersionModeChange(true)}
+              className={cn(
+                'h-7 rounded-full border px-3 text-[11px] transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-sky-200/70',
+                isImmersionMode
+                  ? 'border-white/15 bg-white/10 text-white/90'
+                  : 'border-white/10 bg-transparent text-white/60 hover:text-white/78',
+              )}
+            >
+              몰입
+            </button>
+          </div>
+        </div>
+        <p className="text-[11px] text-white/54">
+          {isImmersionMode ? '필수만 남기고 숨김' : '모든 컨트롤 표시'}
+        </p>
+      </section>
+
       <section className="space-y-2.5 rounded-2xl border border-white/12 bg-black/22 p-3.5 backdrop-blur-md">
         <SectionTitle title="Scene" description={selectedRoom?.name ?? '공간'} />
         <div

src/widgets/space-focus-hud/ui/SpaceFocusHudWidget.tsx

@@ -9,6 +9,7 @@ interface SpaceFocusHudWidgetProps {
   goal: string;
   timerLabel: string;
   visible: boolean;
+  isImmersionMode: boolean;
   onGoalUpdate: (nextGoal: string) => void;
   statusLine: HudStatusLineItem | null;
   onStatusAction: () => void;
@@ -19,6 +20,7 @@ export const SpaceFocusHudWidget = ({
   goal,
   timerLabel,
   visible,
+  isImmersionMode,
   onGoalUpdate,
   statusLine,
   onStatusAction,
@@ -108,7 +110,7 @@ export const SpaceFocusHudWidget = ({
               }
             : null
         }
-        isImmersionMode
+        isImmersionMode={isImmersionMode}
         className="pr-[4.2rem]"
         onGoalCompleteRequest={handleOpenCompleteSheet}
         onStatusAction={onStatusAction}

src/widgets/space-tools-dock/ui/SpaceToolsDockWidget.tsx

@@ -20,6 +20,7 @@ import { QuickSoundPopover } from './popovers/QuickSoundPopover';
 import { InboxToolPanel } from './panels/InboxToolPanel';
 interface SpaceToolsDockWidgetProps {
   isFocusMode: boolean;
+  isImmersionMode: boolean;
   rooms: RoomTheme[];
   selectedRoomId: string;
   selectedTimerLabel: string;
@@ -42,12 +43,14 @@ interface SpaceToolsDockWidgetProps {
   onRestoreThought: (thought: RecentThought) => void;
   onClearInbox: () => RecentThought[];
   onResetToSceneRecommended: () => void;
+  onImmersionModeChange: (next: boolean) => void;
   onStatusMessage: (payload: HudStatusLinePayload) => void;
   onExitRequested: () => void;
 }
 
 export const SpaceToolsDockWidget = ({
   isFocusMode,
+  isImmersionMode,
   rooms,
   selectedRoomId,
   selectedTimerLabel,
@@ -70,6 +73,7 @@ export const SpaceToolsDockWidget = ({
   onRestoreThought,
   onClearInbox,
   onResetToSceneRecommended,
+  onImmersionModeChange,
   onStatusMessage,
   onExitRequested,
 }: SpaceToolsDockWidgetProps) => {
@@ -411,9 +415,11 @@ export const SpaceToolsDockWidget = ({
             rooms={rooms}
             selectedRoomId={selectedRoomId}
             selectedTimerLabel={selectedTimerLabel}
+            isImmersionMode={isImmersionMode}
             sceneRecommendedSoundLabel={sceneRecommendedSoundLabel}
             sceneRecommendedTimerLabel={sceneRecommendedTimerLabel}
             timerPresets={timerPresets}
+            onImmersionModeChange={onImmersionModeChange}
             onSelectRoom={(roomId) => {
               onRoomSelect(roomId);
             }}

src/widgets/space-workspace/ui/SpaceWorkspaceWidget.tsx

@@ -167,6 +167,7 @@ export const SpaceWorkspaceWidget = () => {
   );
 
   const [workspaceMode, setWorkspaceMode] = useState<WorkspaceMode>('setup');
+  const [isImmersionMode, setImmersionMode] = useState(false);
   const [selectedRoomId, setSelectedRoomId] = useState(initialRoomId);
   const [selectedTimerLabel, setSelectedTimerLabel] = useState(initialTimerLabel);
   const [goalInput, setGoalInput] = useState(initialGoal);
@@ -377,6 +378,7 @@ export const SpaceWorkspaceWidget = () => {
         goal={goalInput.trim()}
         timerLabel={selectedTimerLabel}
         visible={isFocusMode}
+        isImmersionMode={isImmersionMode}
         statusLine={activeStatus}
         onStatusAction={runActiveAction}
         onStatusMessage={pushStatusLine}
@@ -405,6 +407,8 @@ export const SpaceWorkspaceWidget = () => {
         onSetSoundVolume={setMasterVolume}
         isSoundMuted={isMuted}
         onSetSoundMuted={setMuted}
+        isImmersionMode={isImmersionMode}
+        onImmersionModeChange={setImmersionMode}
         onCaptureThought={(note) => addThought(note, selectedRoom.name)}
         onDeleteThought={removeThought}
         onSetThoughtCompleted={setThoughtCompleted}