refactor: 后端代码重构，提取通用权限验证逻辑至common模块，减少代码冗余

backend/app/api/memories.py

@@ -12,32 +12,13 @@ from app.services.plot_analyzer import get_plot_analyzer
 from app.services.ai_service import create_user_ai_service
 from app.models.settings import Settings
 from app.logger import get_logger
+from app.api.common import verify_project_access
 import uuid
 
 logger = get_logger(__name__)
 router = APIRouter(prefix="/api/memories", tags=["memories"])
 
 
-async def verify_project_access(project_id: str, user_id: str, db: AsyncSession) -> Project:
-    """验证用户是否有权访问指定项目"""
-    if not user_id:
-        raise HTTPException(status_code=401, detail="未登录")
-    
-    result = await db.execute(
-        select(Project).where(
-            Project.id == project_id,
-            Project.user_id == user_id
-        )
-    )
-    project = result.scalar_one_or_none()
-    
-    if not project:
-        logger.warning(f"项目访问被拒绝: project_id={project_id}, user_id={user_id}")
-        raise HTTPException(status_code=404, detail="项目不存在或无权访问")
-    
-    return project
-
-
 @router.post("/projects/{project_id}/analyze-chapter/{chapter_id}")
 async def analyze_chapter(
     project_id: str,