feat(pop-profile): 앱 모드(풀스크린) 메뉴 항목 추가

POP 프로필 팝오버에 "앱 모드" 메뉴를 추가한다.
Fullscreen API로 브라우저를 전체화면 전환하여 앱처럼 사용 가능.
- showAppMode 설정 옵션 추가 (기본 활성화)
- 풀스크린 진입: document.documentElement.requestFullscreen()
- 풀스크린 해제: document.exitFullscreen()
- 상태에 따라 아이콘/텍스트 전환 (Maximize2/Minimize2, 앱 모드/앱 모드 해제)
- fullscreenchange 이벤트 리스너로 상태 동기화
- 디자이너 설정 패널에 "앱 모드 (풀스크린)" 토글 추가

frontend/lib/registry/pop-components/pop-profile.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import React, { useState, useMemo } from "react";
+import React, { useState, useMemo, useEffect, useCallback } from "react";
 import { useRouter } from "next/navigation";
 import { cn } from "@/lib/utils";
 import { Label } from "@/components/ui/label";
@@ -17,7 +17,7 @@ import {
   PopoverContent,
   PopoverTrigger,
 } from "@/components/ui/popover";
-import { Monitor, LayoutGrid, LogOut, UserCircle } from "lucide-react";
+import { Monitor, LayoutGrid, LogOut, UserCircle, Maximize2, Minimize2 } from "lucide-react";
 import { PopComponentRegistry } from "@/lib/registry/PopComponentRegistry";
 import { useAuth } from "@/hooks/useAuth";
 
@@ -31,6 +31,7 @@ export interface PopProfileConfig {
   avatarSize?: AvatarSize;
   showDashboardLink?: boolean;
   showPcMode?: boolean;
+  showAppMode?: boolean;
   showLogout?: boolean;
 }
 
@@ -38,6 +39,7 @@ const DEFAULT_CONFIG: PopProfileConfig = {
   avatarSize: "md",
   showDashboardLink: true,
   showPcMode: true,
+  showAppMode: true,
   showLogout: true,
 };
 
@@ -67,6 +69,33 @@ function PopProfileComponent({ config: rawConfig }: PopProfileComponentProps) {
   const router = useRouter();
   const { user, isLoggedIn, logout } = useAuth();
   const [open, setOpen] = useState(false);
+  const [isFullscreen, setIsFullscreen] = useState(false);
+
+  // 풀스크린 상태 변경 감지
+  useEffect(() => {
+    const handleFullscreenChange = () => {
+      setIsFullscreen(!!document.fullscreenElement);
+    };
+    document.addEventListener("fullscreenchange", handleFullscreenChange);
+    // 초기 상태 동기화
+    setIsFullscreen(!!document.fullscreenElement);
+    return () => {
+      document.removeEventListener("fullscreenchange", handleFullscreenChange);
+    };
+  }, []);
+
+  const handleAppMode = useCallback(async () => {
+    setOpen(false);
+    try {
+      if (document.fullscreenElement) {
+        await document.exitFullscreen();
+      } else {
+        await document.documentElement.requestFullscreen();
+      }
+    } catch {
+      // 풀스크린 API 미지원 또는 사용자 거부
+    }
+  }, []);
 
   const config = useMemo(() => ({
     ...DEFAULT_CONFIG,
@@ -180,6 +209,20 @@ function PopProfileComponent({ config: rawConfig }: PopProfileComponentProps) {
                     PC 모드
                   </button>
                 )}
+                {config.showAppMode && (
+                  <button
+                    onClick={handleAppMode}
+                    className="flex w-full items-center gap-3 rounded-md px-3 py-3 text-sm transition-colors hover:bg-accent"
+                    style={{ minHeight: 48 }}
+                  >
+                    {isFullscreen ? (
+                      <Minimize2 className="h-4 w-4 text-muted-foreground" />
+                    ) : (
+                      <Maximize2 className="h-4 w-4 text-muted-foreground" />
+                    )}
+                    {isFullscreen ? "앱 모드 해제" : "📱 앱 모드"}
+                  </button>
+                )}
                 {config.showLogout && (
                   <>
                     <div className="mx-2 my-1 border-t" />
@@ -276,6 +319,14 @@ function PopProfileConfigPanel({ config: rawConfig, onUpdate }: PopProfileConfig
           />
         </div>
 
+        <div className="flex items-center justify-between">
+          <Label className="text-xs text-muted-foreground">앱 모드 (풀스크린)</Label>
+          <Switch
+            checked={config.showAppMode ?? true}
+            onCheckedChange={(v) => updateConfig({ showAppMode: v })}
+          />
+        </div>
+
         <div className="flex items-center justify-between">
           <Label className="text-xs text-muted-foreground">로그아웃</Label>
           <Switch
@@ -325,6 +376,7 @@ PopComponentRegistry.registerComponent({
     avatarSize: "md",
     showDashboardLink: true,
     showPcMode: true,
+    showAppMode: true,
     showLogout: true,
   },
   connectionMeta: {