Unify popup UI to TradeAlertModal design system.

Add AppPopup shell, shared CSS, MUI theme overrides, and center positioning for consistent modal styling across frontend and frontend_golden.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/App.tsx

@@ -93,6 +93,7 @@ import type { LoginResponse } from './utils/backendApi';
 import { invalidateAppSettingsCache } from './hooks/useAppSettings';
 import { invalidateIndicatorSettingsCache } from './hooks/useIndicatorSettings';
 import './App.css';
+import './styles/appPopup.css';
 
 let _indCounter = 0;
 function newIndId() { return `ind_${++_indCounter}_${Date.now()}`; }
@@ -1866,19 +1867,17 @@ function App() {
 
           {/* 실시간 전략 체크 패널 */}
           {showLivePanel && menuPage === 'chart' && layoutDef.count === 1 && (
-            <div style={{ position: 'absolute', top: 48, right: 14, zIndex: 60 }}>
-              <LiveStrategyPanel
-                theme={theme}
-                market={symbol}
-                strategies={liveStrategies}
-                settings={liveStrategySettings}
-                watchlistCount={watchlist.length}
-                monitoredMarkets={monitoredMarkets}
-                onClearMarkers={() => { clearLiveMarkers(); managerRef.current?.clearLiveStrategyMarkers(); }}
-                onSettingsChange={handleLiveSettingsChange}
-                onClose={() => setShowLivePanel(false)}
-              />
-            </div>
+            <LiveStrategyPanel
+              theme={theme}
+              market={symbol}
+              strategies={liveStrategies}
+              settings={liveStrategySettings}
+              watchlistCount={watchlist.length}
+              monitoredMarkets={monitoredMarkets}
+              onClearMarkers={() => { clearLiveMarkers(); managerRef.current?.clearLiveStrategyMarkers(); }}
+              onSettingsChange={handleLiveSettingsChange}
+              onClose={() => setShowLivePanel(false)}
+            />
           )}
 
           {/* 백테스팅 설정 모달 */}