Refactor routing and documentation for SPA deployment

- Updated the application to serve the SPA from the root path instead of /map/, enhancing accessibility.
- Modified redirect logic to ensure backward compatibility with old /map/* URLs.
- Adjusted documentation across multiple files to reflect the new routing structure and API endpoints.
- Improved handling of OAuth redirects and session management in the backend.
- Updated frontend configuration to align with the new base URL settings.

frontend-nuxt/nuxt.config.ts

@@ -6,7 +6,7 @@ export default defineNuxtConfig({
   devtools: { enabled: true },
 
   app: {
-    baseURL: '/map/',
+    baseURL: '/',
     pageTransition: { name: 'page', mode: 'out-in' },
     head: {
       title: 'HnH Map',