fix: implement hash-based routing for GitHub Pages

- Replace memory history with hash history to handle direct URL navigation
- Prevents 404 errors when accessing routes directly
- URLs will now use hash-based format (e.g., /#/about)
- https://tanstack.com/router/v1/docs/framework/react/guide/history-types#hash-routing
- https://stackoverflow.com/questions/77466065/using-tanstack-router-with-a-spa-in-github-pages

src/main.tsx

@@ -1,16 +1,20 @@
 import { StrictMode } from 'react'
 import ReactDOM from 'react-dom/client'
 import './index.css'
-import { RouterProvider, createRouter } from '@tanstack/react-router'
+import { RouterProvider, createRouter, createHashHistory } from '@tanstack/react-router'
 import { ThemeProvider } from "@/components/theme/theme-provider"
 
 // Import the generated route tree
 import { routeTree } from './routeTree.gen'
 
+// Create a hash history
+const hashHistory = createHashHistory()
+
 // Create a new router instance
 const router = createRouter({ 
     routeTree,
     basepath: "/monash-grades-calculator/",
+    history: hashHistory,
 })
 
 // Register the router instance for type safety