refactor(markdown): drop parameter defaults from createMarkdownToVueRenderFn

It is internal and its only caller passes every argument; apply the
fallbacks at the call site instead of hiding them in the signature
after the required siteConfig parameter.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/node/markdownToVue.ts

@@ -87,10 +87,10 @@ function getResolutionCache(siteConfig: SiteConfig) {
 
 export async function createMarkdownToVueRenderFn(
   srcDir: string,
-  options: MarkdownOptions = {},
-  base = '/',
-  includeLastUpdatedData = false,
-  cleanUrls = false,
+  options: MarkdownOptions,
+  base: string,
+  includeLastUpdatedData: boolean,
+  cleanUrls: boolean,
   siteConfig: SiteConfig
 ) {
   const md = await createMarkdownRenderer(

src/node/plugin.ts

@@ -126,10 +126,10 @@ export async function createVitePressPlugin(
       if (lastUpdated) await cacheAllGitTimestamps(srcDir)
       markdownToVue = await createMarkdownToVueRenderFn(
         srcDir,
-        markdown,
+        markdown ?? {},
         config.base,
-        lastUpdated,
-        cleanUrls,
+        lastUpdated ?? false,
+        cleanUrls ?? false,
         siteConfig
       )
     },