重构学员证书签发与批量导入流程

backend/app/schemas/learner.py

@@ -25,7 +25,22 @@ class LearnerOut(BaseModel):
     student_no: str | None
     status: str
     remark: str | None
+    certificate_count: int = 0
     created_at: datetime
     updated_at: datetime
 
     model_config = {"from_attributes": True}
+
+
+class LearnerImportError(BaseModel):
+    row_no: int
+    message: str
+
+
+class LearnerImportResult(BaseModel):
+    total_rows: int
+    created_rows: int
+    updated_rows: int
+    unchanged_rows: int
+    failed_rows: int
+    errors: list[LearnerImportError]