fix: 헤더 레이아웃 정리 — 이란 mode-toggle 좌측 배치 + Flag 빈값 표기 수정

- #dashboard-header-slot: flex + justify-content:center 기본 중앙 배치
- 이란 mode-toggle-left: position:absolute left:0 → 탭 오른쪽 배치
- 한국 필터 탭: 중앙 배치 유지
- 감시 목록 Flag 빈값: '??' → '-'

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/App.css

@@ -1991,6 +1991,19 @@
   color: var(--kcg-muted) !important;
 }
 
+#dashboard-header-slot {
+  display: flex;
+  flex: 1;
+  gap: 6px;
+  align-items: center;
+  justify-content: center;
+  position: relative;
+}
+#dashboard-header-slot > .mode-toggle-left {
+  position: absolute;
+  left: 0;
+}
+
 /* ======================== */
 /* Mode Toggle (LIVE/REPLAY) */
 /* ======================== */

frontend/src/components/iran/IranDashboard.tsx

@@ -121,7 +121,7 @@ const IranDashboard = ({
     <>
       {headerSlot && createPortal(
         <>
-          <div className="mode-toggle">
+          <div className="mode-toggle mode-toggle-left">
             <div className="flex items-center gap-1.5 font-mono text-[11px] text-kcg-danger bg-kcg-danger-bg border border-kcg-danger/30 rounded-[6px] px-2.5 py-1 font-bold animate-pulse">
               <span className="text-[13px]">⚔️</span>
               D+{Math.floor((currentTime - new Date('2026-03-01T00:00:00Z').getTime()) / (1000 * 60 * 60 * 24))}

frontend/src/components/korea/KoreaMap.tsx

@@ -784,7 +784,7 @@ export function KoreaMap({ ships, allShips, aircraft, satellites, layers, osintF
                         >
                           <td className="py-0.5 px-1 text-white/60">{s.mmsi}</td>
                           <td className="py-0.5 px-1 text-white/90 truncate max-w-[140px]">{s.name || '-'}</td>
-                          <td className="py-0.5 px-1 text-center text-white/60">{s.flag || '??'}</td>
+                          <td className="py-0.5 px-1 text-center text-white/60">{s.flag || '-'}</td>
                           <td className="py-0.5 px-1 text-white/50">{s.mtCategory || '-'}</td>
                           <td className="py-0.5 px-1 text-right text-white/50">{s.speed?.toFixed(1)}kn</td>
                         </tr>