Fix ESLint and CSS Minimizer errors blocking npm run build (#17)

## Summary
- Closes #16
- Clear unused imports/bindings, empty `{}` prop patterns, `==` vs `===`, and hook dependency gaps across App, contexts, and pages
- Replace invalid `calc(3rem + unset)` in `index.css` so Css Minimizer no longer fails

## Test plan
- [x] `npm run build` in `llm-fe` succeeds (no ESLint / postcss-calc errors)
- [ ] Spot-check SignIn, dashboard, account, feedback, document storage pages still render
- [ ] Confirm WebSocket/message flows still work after MessageContext dep cleanupReviewed-on: #17

llm-fe/src/App.tsx

@@ -1,18 +1,12 @@
 import React, { Component, useContext } from 'react';
 import './App.css';
-import Dashboard from './llm-fe/pages/Dashboard/Dashboard';
-import { Routes, Route, createRoutesFromElements, Outlet, Navigate, useLocation } from 'react-router-dom';
-import { createRoot } from 'react-dom/client';
+import { Routes, Route, Outlet, Navigate } from 'react-router-dom';
 import SignIn from './llm-fe/pages/SignIn/SignIn';
 import PasswordReset from './llm-fe/pages/PasswordReset/PasswordReset';
 import NotFound from './llm-fe/pages/NotFound/NotFound';
-import { AuthContext, AuthProvider } from './llm-fe/contexts/AuthContext';
-import AccountPage from './llm-fe/pages/Account/Account';
-import AsyncDashboard from './llm-fe/pages/AsyncDashboard/AsyncDashboard';
+import { AuthContext } from './llm-fe/contexts/AuthContext';
 import TermsOfService from './llm-fe/pages/TermsOfService/TermsOfService';
 import SetPassword from './llm-fe/components/SetPassword/SetPassword';
-import FeedbackPage from './llm-fe/pages/FeedbackPage/FeedbackPage';
-import { Typography } from '@mui/material';
 import AsyncDashboard2 from './llm-fe/pages/AsyncDashboard2/AsyncDashboard2';
 import FeedbackPage2 from './llm-fe/pages/FeedbackPage2/FeedbackPage2';
 import DocumentStoragePage from './llm-fe/pages/DocumentStoragePage/DocumentStoragePage';
@@ -23,7 +17,7 @@ import GlobalThemeWrapper from './llm-fe/components/GlobalThemeWrapper/GlobalThe
 import Tracker from './llm-fe/components/Tracker/Tracker';
 
 const ProtectedRoutes = () => {
-  const { authenticated, needsNewPassword, loading } = useContext(AuthContext);
+  const { authenticated, loading } = useContext(AuthContext);
   if (loading) {
     return (
       <div>Loading</div>
@@ -84,4 +78,3 @@ class App extends Component {
 }
 
 export default App;
-