项目概览、参与者管理初步优化（未接入真实数据）

backend/app/schemas/study.py

@@ -14,6 +14,10 @@ class StudyCreate(BaseModel):
     protocol_no: Optional[str] = None
     phase: Optional[str] = None
     status: StudyStatus = "DRAFT"
+    visit_interval_days: Optional[int] = None
+    visit_total: Optional[int] = None
+    visit_window_start_offset: Optional[int] = None
+    visit_window_end_offset: Optional[int] = None
 
 
 class StudyUpdate(BaseModel):
@@ -23,6 +27,10 @@ class StudyUpdate(BaseModel):
     protocol_no: Optional[str] = None
     phase: Optional[str] = None
     status: Optional[StudyStatus] = None
+    visit_interval_days: Optional[int] = None
+    visit_total: Optional[int] = None
+    visit_window_start_offset: Optional[int] = None
+    visit_window_end_offset: Optional[int] = None
 
 
 class StudyRead(BaseModel):
@@ -33,6 +41,10 @@ class StudyRead(BaseModel):
     protocol_no: Optional[str]
     phase: Optional[str]
     status: StudyStatus
+    visit_interval_days: Optional[int]
+    visit_total: Optional[int]
+    visit_window_start_offset: Optional[int]
+    visit_window_end_offset: Optional[int]
     created_by: Optional[uuid.UUID]
     created_at: datetime