feat: 统一后端分页查询与前端服务层适配

后端新增通用分页模块，为报销单、员工、预算、agent 资产等
端点统一接入分页参数和游标查询，优化 repository 层分页实
现，前端服务层适配分页响应结构，完善预算图表和全局样式，
优化侧边栏和企业选择器组件，引入 Element Plus 插件注册。

server/src/app/api/v1/endpoints/employees.py

@@ -7,7 +7,8 @@ from fastapi.responses import Response
 from sqlalchemy.orm import Session
 
 from app.api.deps import get_db
-from app.schemas.common import ErrorResponse
+from app.api.pagination import PageNumber, PageSize, page_payload, wants_page
+from app.schemas.common import ErrorResponse, PaginatedResponse
 from app.schemas.employee import (
     EmployeeCreate,
     EmployeeImportResultRead,
@@ -16,6 +17,7 @@ from app.schemas.employee import (
     EmployeeUpdate,
 )
 from app.services.employee import EmployeeService
+from app.services.employee_pagination import EmployeePaginationService
 
 router = APIRouter()
 DbSession = Annotated[Session, Depends(get_db)]
@@ -33,7 +35,7 @@ def get_employee_meta(db: DbSession) -> EmployeeMetaRead:
 
 @router.get(
     "",
-    response_model=list[EmployeeRead],
+    response_model=list[EmployeeRead] | PaginatedResponse[EmployeeRead],
     summary="查询员工列表",
     description="按状态和关键字筛选员工目录。",
 )
@@ -47,7 +49,18 @@ def list_employees(
         str | None,
         Query(description="姓名、工号、邮箱等关键字模糊查询。"),
     ] = None,
-) -> list[EmployeeRead]:
+    page: PageNumber = None,
+    page_size: PageSize = None,
+) -> list[EmployeeRead] | PaginatedResponse[EmployeeRead]:
+    if wants_page(page, page_size):
+        return page_payload(
+            EmployeePaginationService(db).list_employees_page(
+                status=status_filter,
+                keyword=keyword,
+                page=page,
+                page_size=page_size,
+            )
+        )
     return EmployeeService(db).list_employees(status=status_filter, keyword=keyword)