refactor(build): use async fs and minify while rendering pages

Swap the remaining sync fs calls in renderPage for fs/promises,
switch head-script minification to the async minify API, and make
resolvePageImports async for the realpath call. Pages render under
buildConcurrency, so blocking calls here stall the whole batch.

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

src/node/build/render.ts

@@ -1,8 +1,7 @@
 import { isBooleanAttr } from '@vue/shared'
-import fs from 'node:fs'
+import { mkdir, realpath, rm, writeFile } from 'node:fs/promises'
-import { mkdir, writeFile } from 'node:fs/promises'
 import path from 'node:path'
-import { minifySync, normalizePath, type Rolldown } from 'vite'
+import { minify, normalizePath, type Rolldown } from 'vite'
 import { version } from '../../../package.json'
 import type { SiteConfig } from '../config'
 import {
@@ -86,7 +85,7 @@ export async function renderPage(
               // resolve imports for index.js + page.md.js and inject script tags
               // for them as well so we fetch everything as early as possible
               // without having to wait for entry chunks to parse
-              ...resolvePageImports(config, page, result, appChunk),
+              ...(await resolvePageImports(config, page, result, appChunk)),
               pageClientJsFileName
             ])
           ]
@@ -148,7 +147,7 @@ export async function renderPage(
     if (matchingChunk) {
       if (!matchingChunk.code.includes('import')) {
         inlinedScript = `<script type="module">${matchingChunk.code}</script>`
-        fs.rmSync(path.resolve(config.outDir, matchingChunk.fileName), {
+        await rm(path.resolve(config.outDir, matchingChunk.fileName), {
           force: true
         })
       } else {
@@ -208,7 +207,7 @@ export async function renderPage(
   await writeFile(htmlFileName, transformedHtml || html)
 }
 
-function resolvePageImports(
+async function resolvePageImports(
   config: SiteConfig,
   page: string,
   result: Rolldown.RolldownOutput,
@@ -220,7 +219,7 @@ function resolvePageImports(
   let srcPath = path.resolve(config.srcDir, page)
   try {
     if (!config.vite?.resolve?.preserveSymlinks) {
-      srcPath = fs.realpathSync(srcPath)
+      srcPath = await realpath(srcPath)
     }
   } catch (e) {
     // if the page is a virtual page generated by a dynamic route this would
@@ -248,7 +247,7 @@ async function renderHead(head: HeadConfig[]): Promise<string> {
           tag === 'script' &&
           (attrs.type === undefined || attrs.type.includes('javascript'))
         ) {
-          innerHTML = minifySync('inline-script.js', innerHTML).code
+          innerHTML = (await minify('inline-script.js', innerHTML)).code
         }
         return `${openTag}${innerHTML}</${tag}>`
       } else {