refactor: 四端完成 Options API → script setup + vuex → pinia 迁移

- buyer(95) / seller(169) / im(53) / manager(280) 共 597 个组件全部从 Options API 转换为 <script setup>
- 四端 vuex 全部移除，状态管理统一迁移至 pinia 4（stores/ 目录）
- util.js 等基础设施去除 vm 首参依赖；全局属性（$Message/$filters 等）在 script 内改为具名导入
- 被外部 ref 访问的公共组件均已补齐 defineExpose（清单见各端 MIGRATION-VUE3.md）
- 各端 eslint 启用 vue/component-api-style 防止新代码回退 Options API
- 四端 yarn build 全部通过；迁移约定与注意事项已更新至各端 MIGRATION-VUE3.md

buyer/src/App.vue

@@ -4,71 +4,78 @@
   </div>
 </template>
 
-<script>
+<script setup>
+import { onMounted } from "vue";
+import { useRoute } from "vue-router";
 import storage from "@/plugins/storage";
 import { getBaseSite, getThemeSetting } from "@/api/common.js";
 import { fetchAndApplyTheme } from "@/utils/theme";
+import { useAppStore } from "@/stores/app";
 
-export default {
-  name: "App",
-  mounted() {
-    this.init();
-  },
-  methods: {
-    applySiteInfo(data) {
-      const expirationTime = new Date().setHours(new Date().getHours() + 1);
-      storage.setItem("sitelogo_expiration_time", expirationTime);
-      storage.setItem("siteName", data.siteName);
-      storage.setItem("logoImg", data.buyerSideLogo);
-      storage.setItem("siteIcon", data.buyerSideIcon);
-      this.$store.commit("SET_SITENAME", data.siteName);
-      this.$store.commit("SET_LOGOIMG", data.buyerSideLogo);
-      if (this.$route.meta.title === undefined) {
-        window.document.title = data.siteName;
+defineOptions({ name: "App" });
+
+const route = useRoute();
+const appStore = useAppStore();
+
+function applySiteInfo(data) {
+  const expirationTime = new Date().setHours(new Date().getHours() + 1);
+  storage.setItem("sitelogo_expiration_time", expirationTime);
+  storage.setItem("siteName", data.siteName);
+  storage.setItem("logoImg", data.buyerSideLogo);
+  storage.setItem("siteIcon", data.buyerSideIcon);
+  appStore.setSiteName(data.siteName);
+  appStore.setLogoImg(data.buyerSideLogo);
+  if (route.meta.title === undefined) {
+    window.document.title = data.siteName;
+  }
+  let link =
+    document.querySelector("link[rel*='icon']") ||
+    document.createElement("link");
+  link.type = "image/x-icon";
+  link.href = data.buyerSideIcon;
+  link.rel = "shortcut icon";
+  document.getElementsByTagName("head")[0].appendChild(link);
+}
+
+function init() {
+  const expirationTime = storage.getItem("sitelogo_expiration_time");
+  const cacheValid =
+    expirationTime && new Date() <= new Date(Number(expirationTime));
+  if (cacheValid) {
+    applySiteInfo({
+      siteName: storage.getItem("siteName"),
+      buyerSideLogo: storage.getItem("logoImg"),
+      buyerSideIcon: storage.getItem("siteIcon"),
+    });
+  }
+  getSite();
+  getTheme();
+}
+
+function getSite() {
+  getBaseSite().then((res) => {
+    if (res.success && res.result.settingValue) {
+      try {
+        const data = JSON.parse(res.result.settingValue);
+        applySiteInfo(data);
+      } catch {
+        // 站点配置解析失败时使用缓存
       }
-      let link =
-        document.querySelector("link[rel*='icon']") ||
-        document.createElement("link");
-      link.type = "image/x-icon";
-      link.href = data.buyerSideIcon;
-      link.rel = "shortcut icon";
-      document.getElementsByTagName("head")[0].appendChild(link);
-    },
-    init() {
-      const expirationTime = storage.getItem("sitelogo_expiration_time");
-      const cacheValid =
-        expirationTime && new Date() <= new Date(Number(expirationTime));
-      if (cacheValid) {
-        this.applySiteInfo({
-          siteName: storage.getItem("siteName"),
-          buyerSideLogo: storage.getItem("logoImg"),
-          buyerSideIcon: storage.getItem("siteIcon"),
-        });
-      }
-      this.getSite();
-      this.getTheme();
-    },
-    getSite() {
-      getBaseSite().then((res) => {
-        if (res.success && res.result.settingValue) {
-          try {
-            const data = JSON.parse(res.result.settingValue);
-            this.applySiteInfo(data);
-          } catch {
-            // 站点配置解析失败时使用缓存
-          }
-        }
-      }).catch((err) => {
-        console.warn('获取站点配置失败', err);
-      });
-    },
-    getTheme() {
-      fetchAndApplyTheme(getThemeSetting).catch((err) => {
-        console.warn('获取主题配置失败', err);
-      });
-    },
-  },
-};
+    }
+  }).catch((err) => {
+    console.warn('获取站点配置失败', err);
+  });
+}
+
+function getTheme() {
+  fetchAndApplyTheme(getThemeSetting).catch((err) => {
+    console.warn('获取主题配置失败', err);
+  });
+}
+
+onMounted(() => {
+  init();
+});
 </script>
 <style lang="scss">
 #app {