修复前后端显示异常问题（受试者、中心、负责人、日期等）

backend/app/schemas/milestone.py

@@ -4,12 +4,21 @@ from typing import Optional
 
 from pydantic import BaseModel, ConfigDict, Field
 
+from app.schemas.user import UserDisplay
+
+
+class SiteDisplay(BaseModel):
+    id: uuid.UUID
+    name: Optional[str] = None
+
+    model_config = ConfigDict(from_attributes=True)
 
 class MilestoneCreate(BaseModel):
     type: str
     name: Optional[str] = None
     planned_date: Optional[date] = None
     owner_id: Optional[uuid.UUID] = None
+    site_id: Optional[uuid.UUID] = None
     notes: Optional[str] = None
     status: str = Field(default="NOT_STARTED")
 
@@ -20,6 +29,7 @@ class MilestoneUpdate(BaseModel):
     actual_date: Optional[date] = None
     status: Optional[str] = None
     owner_id: Optional[uuid.UUID] = None
+    site_id: Optional[uuid.UUID] = None
     notes: Optional[str] = None
 
 
@@ -32,6 +42,9 @@ class MilestoneRead(BaseModel):
     actual_date: Optional[date]
     status: str
     owner_id: Optional[uuid.UUID]
+    site_id: Optional[uuid.UUID] = None
+    owner: Optional[UserDisplay] = None
+    site: Optional[SiteDisplay] = None
     notes: Optional[str]
     created_at: datetime
     updated_at: datetime