style: simplify rspress config imports

Agent-Logs-Url: https://github.com/rstackjs/rstack-examples/sessions/2a336486-a4eb-439c-8a87-2d6ef6a5942d

Author: Copilot

rspress/basic/rspress.config.ts

@@ -1,4 +1,4 @@
-import * as path from 'node:path';
+import path from 'node:path';
 import { defineConfig } from '@rspress/core';
 
 export default defineConfig({

rspress/custom-theme/rspress.config.ts

@@ -1,4 +1,4 @@
-import * as path from 'node:path';
+import path from 'node:path';
 import { defineConfig } from '@rspress/core';
 
 export default defineConfig({