feat: export cacheAllGitTimestamps and getGitTimestamp

x-ref: https://github.com/vuejs/vitepress/issues/4954#issuecomment-3337312956

src/node/index.ts

@@ -2,18 +2,19 @@ export { loadEnv, type Plugin } from 'vite'
 export * from './build/build'
 export * from './config'
 export * from './contentLoader'
+export type { DefaultTheme } from './defaultTheme'
 export * from './init/init'
 export * from './markdown/markdown'
-export { defineLoader, type LoaderModule } from './plugins/staticDataPlugin'
 export {
   defineRoutes,
   type ResolvedRouteConfig,
   type RouteModule
 } from './plugins/dynamicRoutesPlugin'
+export { defineLoader, type LoaderModule } from './plugins/staticDataPlugin'
 export * from './postcss/isolateStyles'
 export * from './serve/serve'
 export * from './server'
-export type { DefaultTheme } from './defaultTheme'
+export * from './utils/getGitTimestamp'
 
 // shared types
 export type { HeadConfig, Header, SiteData } from '../../types/shared'