feat(schemas): 扩充 Task/Product Pydantic Schema

Task Schema:
- TaskResponse 新增 is_rework, reject_reason, received_at, completed_at, records, product_sn
- 新增 TaskRejectRequest, TaskTransferRequest, TaskRecordCreate, TaskRecordResponse
- TaskRecordResponse 含 json.loads 反序列化 images

Product Schema:
- ProductResponse/ProductScanResponse 新增 external_serial, current_location_id, overall_status
- ProductScanResponse 新增 task_tree (递归任务树)
- ProductCreate 改为 material_id/material_name/spec_model + external_serial + order_no 自由文本
- ProductUpdate 新增 order_no

backend/app/schemas/task.py

@@ -59,6 +59,35 @@ class TaskTransferRequest(BaseModel):
     note: str | None = Field(None, description="交接备注")
 
 
+class TaskRecordCreate(BaseModel):
+    """任务进度记录 — 备注 + 图片"""
+    remark: str = Field("", max_length=2000, description="备注文本")
+    images: list[str] = Field(default_factory=list, description="图片 URL 列表")
+
+
+class TaskRecordResponse(BaseModel):
+    id: int
+    task_id: uuid.UUID
+    remark: str | None = None
+    images: list[str] = []
+    created_at: datetime | None = None
+
+    model_config = {"from_attributes": True}
+
+    @classmethod
+    def model_validate(cls, obj, **kwargs):
+        """处理 DB 中 images 的 JSON 字符串 → list 反序列化"""
+        import json
+        if hasattr(obj, "images") and isinstance(obj.images, str):
+            try:
+                obj.images = json.loads(obj.images)
+            except (json.JSONDecodeError, TypeError):
+                obj.images = []
+        elif hasattr(obj, "images") and obj.images is None:
+            obj.images = []
+        return super().model_validate(obj, **kwargs)
+
+
 # ============================================================
 # 响应模型
 # ============================================================
@@ -85,6 +114,8 @@ class TaskResponse(BaseModel):
     """任务详情响应 — 递归包含所有子任务"""
     id: uuid.UUID
     product_id: uuid.UUID
+    product_sn: str = ""
+    product_material: str = ""
     parent_task_id: uuid.UUID | None
     task_name: str
     assignee_id: str | None
@@ -96,6 +127,7 @@ class TaskResponse(BaseModel):
     completed_at: datetime | None = None
     created_at: datetime
     child_tasks: list[TaskResponse] = []
+    records: list[TaskRecordResponse] = []
 
     model_config = {"from_attributes": True}