Fix Flask-Login user loader to support cookie fallback

- Enhanced user_loader to check cookies when session is empty
- Restore session data from auth cookies automatically
- Enable @login_required decorators to work with cookie authentication
- Fix API endpoints 302 redirect issues

api.py

@@ -222,7 +222,26 @@ def load_user(user_id):
     print(f"Session data in user_loader: {dict(session)}")
     print(f"Current request cookies: {request.cookies}")
     
-    # user_id가 문자열로 전달되기 때문에 사용자 ID로 처리
+    # Check session first, then fallback to cookies
+    session_user_id = session.get('user_id')
+    if not session_user_id:
+        # Try to get from cookies
+        cookie_user_id = request.cookies.get('auth_user_id')
+        cookie_username = request.cookies.get('auth_username')
+        print(f"Session empty, checking cookies: user_id={cookie_user_id}, username={cookie_username}")
+        
+        if cookie_user_id and cookie_username:
+            # Verify cookie user exists
+            for username, user in users.items():
+                if str(user.id) == str(cookie_user_id) and username == cookie_username:
+                    print(f"User found via cookies: {username}, ID: {user.id}")
+                    # Restore session from cookies
+                    session['user_id'] = user.id
+                    session['username'] = username
+                    session.modified = True
+                    return user
+    
+    # Original session-based lookup
     for username, user in users.items():
         if str(user.id) == str(user_id):  # 확실한 문자열 비교
             print(f"User found: {username}, ID: {user.id}")