reason: Backend architecture overview and pre-development checklist for the JSP + Servlet + MySQL system.


reason: Backend source layout conventions for Servlet, service, DAO, entity, and config files.


reason: MySQL schema, DAO CRUD, keys, and transaction guidance for login and role persistence.


reason: Validation, authentication failure, service failure, and safe Servlet response handling.


reason: Guidance for operation logs and exception tracing in authentication-related code.


reason: Layer boundary and backend quality constraints for implementation.


reason: Frontend overview for JSP/CSS presentation served by Servlet/Tomcat.


reason: JSP, include, static CSS/JS/image placement conventions.


reason: JSP fragment, form, table, and reusable UI conventions for login views.


reason: Constraint that React/Vue hooks and SPA conventions should not be introduced.


reason: Server-rendered request/session/form state conventions for login flow.


reason: JSP/Servlet validation and JavaBean display contract guidance.


reason: JSP/CSS quality and UI verification guidance.