fix: 修复 episodes + yearly_targets 模型导入缺失，增 DELETE 接口，冒烟 6/6 全绿

backend/app/api/yearly_targets.py

@@ -1,5 +1,5 @@
 """
-年度收视目标 API — 增改查
+年度收视目标 API — 增删改查
 
 业务规则（.clinerules 5.2 只增不改）:
   - yearly_targets.year 有 UNIQUE 约束
@@ -13,6 +13,7 @@ from sqlmodel import Session, select
 from app.core.deps import get_current_user, require_role
 from app.db.session import get_session
 from app.models.user import User, UserRole
+from app.models.yearly_target import YearlyTarget
 from app.schemas.yearly_target import YearlyTargetCreate, YearlyTargetResponse, YearlyTargetUpdate
 
 router = APIRouter(prefix="/api/yearly_targets", tags=["年度目标"])
@@ -93,4 +94,19 @@ def update_target(
     session.add(target)
     session.commit()
     session.refresh(target)
-    return target
+    return target
+
+
+@router.delete("/{target_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_target(
+    target_id: int,
+    session: Session = Depends(get_session),
+    current_user: User = Depends(require_role(UserRole.zhipianren, UserRole.zebian)),
+):
+    """删除年度目标（仅管理员/责编）。"""
+    target = session.get(YearlyTarget, target_id)
+    if target is None:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="目标不存在")
+    session.delete(target)
+    session.commit()
+    return None