Refactor app by modularizing components and extracting utilities.

The changes split large features into smaller, reusable components like `AdminPanel`, `LoginPage`, `TopBar`, `PasswordModal`, and `ChipModal`. Utility functions such as `cycleTag` and `chipStorage` were extracted for better organization. This improves the code's readability, maintainability, and scalability.

frontend/src/constants.js

@@ -0,0 +1,2 @@
+export const API_BASE = "/api";
+export const CHIP_LIST = ["AL", "JG", "JN", "SN", "TL"];