chore: 将前端移动到 client/ 目录，准备合并为单仓库

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

client/src/store/editors.ts

@@ -0,0 +1,22 @@
+import { useStorage } from "@vueuse/core"
+import { STORAGE_KEY } from "../utils/const"
+
+const defaultHTML = ``
+const defaultCSS = ``
+
+export const html = useStorage(STORAGE_KEY.HTML, defaultHTML)
+export const css = useStorage(STORAGE_KEY.CSS, defaultCSS)
+export const js = useStorage(STORAGE_KEY.JS, "")
+
+export const tab = useStorage(STORAGE_KEY.TAB, "html")
+export const size = useStorage(STORAGE_KEY.FONTSIZE, 24)
+
+export function reset(lang: "html" | "css" | "js") {
+  if (lang === "html") {
+    html.value = defaultHTML
+  } else if (lang === "css") {
+    css.value = defaultCSS
+  } else {
+    js.value = ""
+  }
+}