fix: correct Material UI icon naming in Header.tsx and update timetable components

- Fix icon naming: remove 'Icon' suffix from MUI icon components in Header.tsx
  (AccessTime, Close, Person, School, Schedule, Class, Book, Settings, Student, Login, Logout)
- Update timetable components to use UserContext instead of ProfileContext
- Fix timetableService naming collision and circular reference
- Update various components for consistency

src/pages/user/NotFound.tsx

@@ -36,7 +36,7 @@ function NotFound() {
                     gap: 3
                 }}
             >
-                <ErrorOutlineIcon sx={{ fontSize: 60, color: theme.palette.error.main }} />
+                <ErrorOutline sx={{ fontSize: 60, color: theme.palette.error.main }} />
                 <Typography variant="h2" component="h1" gutterBottom>
                     404
                 </Typography>