fix: remove dead code in ai_summary + unused import in leaves API

Co-Authored-By: Claude <noreply@anthropic.com>

backend/app/api/leaves.py

@@ -2,7 +2,7 @@ from uuid import UUID
 from fastapi import APIRouter, Depends, Query, HTTPException
 from sqlalchemy.ext.asyncio import AsyncSession
 from app.database import get_db
-from app.middleware.auth import get_current_user, RoleChecker
+from app.middleware.auth import get_current_user
 from app.schemas.leave import LeaveCreate, LeaveUpdate
 from app.services import leaves as leave_service
 

backend/app/services/ai_summary.py

@@ -150,8 +150,6 @@ def build_summary_prompt(
                 f"{lv.get('start_date', '')} ~ {lv.get('end_date', '')} "
                 f"({lv.get('days', 0)}天)\n"
             )
-        if not leaves:
-            data_block += "无请假记录\n"
     else:
         data_block += "\n## 本周请假情况\n无请假记录\n"