perf: skulpt 改为按需加载，client-zip 换成 fflate

skulpt 此前被 SubmitCode.vue 静态引用，945K 的 chunk 落在做题页首屏，
学生打开任何一道题都要下 233KB gzip，只为提交时拿一个语法错误行号。
改成 import() 懒加载并在语言切到 Python3 时预取，加载失败放行提交、
交给后端判题兜底。构建产物确认该 chunk 只剩一处 import() 引用，
index.html 不再引用。

client-zip 的能力 fflate 已经覆盖（utils/functions.ts 本就在用 zlibSync），
新增 createZipBlob 统一两处测试用例打包，删掉该依赖。压缩方式由 store
变为 deflate，Python zipfile 透明解压，后端不受影响。

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

src/admin/problem/components/SQLTestcaseEditor.vue

@@ -1,6 +1,6 @@
 <script setup lang="ts">
-import { downloadZip } from "client-zip"
 import type { LANGUAGE, SQLDisplay, Testcase } from "utils/types"
+import { createZipBlob } from "utils/functions"
 import SQLDataTable from "oj/problem/components/SQLDataTable.vue"
 import {
   generateSQLTestcase,
@@ -156,15 +156,13 @@ async function preview() {
 async function upload() {
   isUploading.value = true
   try {
-    const now = new Date()
     const data = scripts.value
       .filter((s) => s.sql.trim())
       .map((s, i) => ({
         name: `${i + 1}.sql`,
-        input: s.sql,
-        lastModified: now,
+        content: s.sql,
       }))
-    const blob = await downloadZip(data).blob()
+    const blob = createZipBlob(data)
     const file = new File([blob], "testcase.zip", { type: "application/zip" })
 
     const res = await uploadTestcases(file, { sql: true })

src/admin/problem/components/TestcaseGenerator.vue

@@ -1,6 +1,6 @@
 <script setup lang="ts">
-import { downloadZip } from "client-zip"
 import type { LANGUAGE, Testcase } from "utils/types"
+import { createZipBlob } from "utils/functions"
 import { createTestSubmission } from "utils/judge"
 import { uploadTestcases } from "../../api"
 
@@ -158,15 +158,14 @@ async function run() {
 async function upload() {
   isUploading.value = true
   try {
-    const now = new Date()
     const data = files.value
       .filter((f) => f.in.trim() && f.out && !f.error)
       .flatMap((f, i) => [
-        { name: `${i + 1}.in`, input: f.in, lastModified: now },
-        { name: `${i + 1}.out`, input: f.out, lastModified: now },
+        { name: `${i + 1}.in`, content: f.in },
+        { name: `${i + 1}.out`, content: f.out },
       ])
 
-    const blob = await downloadZip(data).blob()
+    const blob = createZipBlob(data)
     const file = new File([blob], "testcase.zip", { type: "application/zip" })
 
     const res = await uploadTestcases(file)