Add installable PWA shell with safe updates and offline status

web/vite.config.ts

@@ -1,9 +1,33 @@
 import vue from '@vitejs/plugin-vue'
+import { createHash } from 'node:crypto'
+import { readFileSync } from 'node:fs'
 import { defineConfig } from 'vitest/config'
 
 export default defineConfig({
   plugins: [
     vue(),
+    {
+      name: 'rawmark-pwa',
+      apply: 'build',
+      enforce: 'post',
+      generateBundle(_options, bundle) {
+        // 缓存列表由产物生成，覆盖懒加载资源，旧页面更新后仍能加载其依赖。
+        const files = Object.keys(bundle).filter((name) => name === 'index.html' || name.startsWith('assets/')).sort()
+        const version = createHash('sha256')
+        for (const name of files) {
+          const item = bundle[name]!
+          version.update(name).update(item.type === 'chunk' ? item.code : item.source)
+        }
+        for (const name of ['manifest.webmanifest', 'icon.svg', 'icons/icon-192.png', 'icons/icon-512.png', 'icons/maskable-512.png', 'icons/apple-touch-icon.png']) {
+          version.update(readFileSync(new URL('./public/' + name, import.meta.url)))
+          files.push(name)
+        }
+        const source = readFileSync(new URL('./src/service-worker.js', import.meta.url), 'utf8')
+          .replace('__VERSION__', version.digest('hex').slice(0, 16))
+          .replace('__PRECACHE__', JSON.stringify(files.map((name) => '/' + name)))
+        this.emitFile({ type: 'asset', fileName: 'sw.js', source })
+      },
+    },
     // 开发服务器中把分享地址 /s/{token} 交给分享页入口（生产环境由 Go 服务处理）
     {
       name: 'rawmark-share-route',