feat: 信息架构重组 + 变更追踪 + 图片预览增强

- 信息架构重组: 周报精简为拜访+纪要两个Tab，工作计划/商机/要客独立为侧边栏「工作」分组下的独立页面
- 侧边栏分组: 汇总/工作/管理三层分组，仪表盘四卡可点击跳转
- 变更追踪(edit_log): 5张表新增JSONB edit_log列，POST创建/PUT diff自动记录，编辑弹窗变更时间轴，表格🕐编辑标记
- 图片预览增强: ImagePreview统一组件，支持适应页面/缩放/拖拽平移/滚轮缩放/键盘快捷键
- 修复客户导入500错误(errors变量未初始化)
- 移除工作计划/商机/要客页面冗余编辑按钮

Co-Authored-By: Claude <noreply@anthropic.com>

backend/app/api/visits.py

@@ -12,6 +12,7 @@ from app.models.user import User
 from app.schemas.visit import VisitCreate, VisitUpdate, VisitOut, VisitListOut
 from app.utils.timezone import today_cst, parse_date
 from app.services.minio_client import delete_objects
+from app.utils.edit_log import compute_diff, append_entry, init_entry
 
 router = APIRouter(prefix="/visits", tags=["Visits"])
 
@@ -42,6 +43,7 @@ async def _enrich_visit(visit: Visit, db: AsyncSession) -> dict:
         "photos": visit.photos,
         "manager_id": str(visit.manager_id),
         "manager_name": manager_name,
+        "edit_log": visit.edit_log or [],
         "created_at": str(visit.created_at),
         "updated_at": str(visit.updated_at),
     }
@@ -138,6 +140,7 @@ async def create_visit(
         photos=data.photos,
         manager_id=uuid.UUID(current_user["user_id"]),
     )
+    init_entry(visit, current_user["name"])
     db.add(visit)
 
     # Create draft copies for companions
@@ -176,6 +179,14 @@ async def update_visit(
     if current_user["role"] == "manager" and str(visit.manager_id) != current_user["user_id"]:
         raise HTTPException(status_code=403, detail="Access denied")
 
+    # Snapshot old values for diff
+    old_snapshot = {
+        "customer_id": str(visit.customer_id), "visit_date": str(visit.visit_date),
+        "visit_method": visit.visit_method, "time_range": visit.time_range,
+        "visitor_name": visit.visitor_name or "", "visitor_phone": visit.visitor_phone or "",
+        "communication_content": visit.communication_content, "customer_demand": visit.customer_demand,
+    }
+
     update_data = data.model_dump(exclude_unset=True)
     if "visit_date" in update_data and update_data["visit_date"]:
         update_data["visit_date"] = parse_date(update_data["visit_date"])
@@ -183,6 +194,17 @@ async def update_visit(
     for key, value in update_data.items():
         setattr(visit, key, value)
 
+    # Compute diff and append to edit_log
+    new_snapshot = {
+        "customer_id": str(visit.customer_id), "visit_date": str(visit.visit_date),
+        "visit_method": visit.visit_method, "time_range": visit.time_range,
+        "visitor_name": visit.visitor_name or "", "visitor_phone": visit.visitor_phone or "",
+        "communication_content": visit.communication_content, "customer_demand": visit.customer_demand,
+    }
+    changes = compute_diff(old_snapshot, new_snapshot)
+    if changes:
+        append_entry(visit, current_user["name"], changes, getattr(data, "edit_reason", None))
+
     await db.commit()
     await db.refresh(visit)
     return await _enrich_visit(visit, db)