Add remember me session handling

[gaidheal1]

Summary

• Add a remember me checkbox to login and route auth tokens through shared storage helpers
• Store short sessions in sessionStorage, remembered sessions in localStorage, and keep refresh/websocket flows aligned
• Extend JWT issuance to support longer remembered refresh tokens and add login/session tests

Validation (from original PR #312)

• ESLint on changed frontend files
• Vitest: Home, LoginPage, authStorage tests
• Backend: remember-me auth tests; broader users/api suite