chore: update vercel.json for new /docs routing and set base path in vite.config.ts and router.tsx

apps/docs/src/router.tsx

@@ -4,6 +4,7 @@ import { routeTree } from './routeTree.gen';
 
 export function getRouter() {
   return createTanStackRouter({
+    basepath: '/docs',
     defaultNotFoundComponent: NotFound,
     defaultPreload: 'intent',
     routeTree,

apps/docs/vite.config.ts

@@ -7,6 +7,7 @@ import { tanstackStart } from '@tanstack/react-start/plugin/vite';
 import tsConfigPaths from 'vite-tsconfig-paths';
 
 export default defineConfig({
+  base: '/docs/',
   server: {
     port: 3000
   },