refactor(web): update API service, view script and add tests

Frontend:
- services/api.js: update API service client
- views/scripts/EmployeeManagementView.js: update employee management view script
- tests/api-request.test.mjs: update API request tests

Scripts:
- create_employee.sh: add employee creation script

create_employee.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+export PYTHONIOENCODING=utf-8
+export LC_ALL=C.UTF-8
+export LANG=C.UTF-8
+
+cd /app/server && .venv/bin/python3 /tmp/create_employee_input.py