Modularize frontend CSS and JavaScript assets

将所有API Key相关表述和变量名称调整为认证令牌

feat: Refactor Gemini proxy with native types; add Chinese license

Refactor header styling; simplify login form.

Refine login page UI and user experience

Refactor: Enhance UI, improve documentation, and streamline setup

Improve login and client-side access control

Initial project setup