fix: add proper TypeScript types for routeDiscovery configuration

Author: ScriptedAlchemy

src/index.ts

@@ -86,7 +86,6 @@ export const pluginReactRouter = (
       basename = '/',
       buildDirectory = 'build',
       ssr = true,
-      routeDiscovery = { mode: 'lazy', manifestPath: '/__manifest' },
     } = await jiti
       .import<Config>('./react-router.config.ts', {
         default: true,
@@ -98,6 +97,9 @@ export const pluginReactRouter = (
         return {} as Config;
       });
 
+    // Set default routeDiscovery configuration
+    const routeDiscovery = { mode: 'lazy', manifestPath: '/__manifest' } as const;
+
     const routesPath = findEntryFile(resolve(appDirectory, 'routes'));
 
     // Then read the routes