Feat:collab session badge and info mode pins

src/features/map/collaboration/ShareCollabButton.tsx

@@ -1,6 +1,7 @@
 'use client';
 
 import { useState } from 'react';
+import { useRouter } from 'next/navigation';
 import styled from '@emotion/styled';
 import { HugeiconsIcon } from '@hugeicons/react';
 import { UserAdd01Icon, CheckmarkCircle01Icon } from '@hugeicons/core-free-icons';
@@ -43,20 +44,27 @@ const Btn = styled.button<{ $copied: boolean }>`
 
 export function ShareCollabButton() {
   const { isLoggedIn } = useAuth();
+  const router = useRouter();
   const [copied, setCopied] = useState(false);
 
   if (!isLoggedIn) return null;
 
   function handleShare() {
-    const roomId = crypto.randomUUID();
+    // 이미 방에 있으면 현재 URL 재사용, 아니면 새 방 생성 후 URL 교체
+    const params = new URLSearchParams(window.location.search);
+    const existingRoom = params.get('room');
+    const roomId = existingRoom ?? crypto.randomUUID();
     const url = `${window.location.origin}/map?room=${roomId}`;
 
+    if (!existingRoom) {
+      router.replace(`/map?room=${roomId}`);
+    }
+
     navigator.clipboard.writeText(url).then(() => {
       setCopied(true);
-      toast.success('친구 초대 링크가 복사됐어요!', { description: '링크를 붙여넣어 친구에게 공유하세요.' });
+      toast.success('친구 초대 링크가 복사됐어요!', { description: '이 링크는 72시간 동안 유지돼요. 붙여넣어 친구에게 공유하세요.' });
       setTimeout(() => setCopied(false), 2500);
     }).catch(() => {
-      // fallback: select text manually isn't possible here, just show the URL
       toast.info('링크 복사 실패', { description: url });
     });
   }