fix: 🐛 (keep-alive)重构缓存机制

- 移除 KeepCache 组件，直接在 AppMain 中实现缓存逻辑

- 将 fullPath 做为组件缓存的 name

src/views/demo/multi-level/level1.vue

@@ -1,21 +1,10 @@
 <template>
-  <div p-30px>
-    <el-link
-      href="https://gitee.com/youlaiorg/vue3-element-admin/blob/master/src/views/demo/multi-level/level1.vue"
-      type="primary"
-      target="_blank"
-      class="mb-10"
-    >
-      示例源码 请点击>>>>
-    </el-link>
-
-    <div flex flex-col gap-20px>
-      <el-alert :closable="false" title="菜单一级" />
-      <KeepCache />
-    </div>
-  </div>
+  <el-alert :closable="false" title="菜单一级" />
 </template>
 <script setup lang="ts">
-import KeepCache from "@/components/KeepCache/index.vue";
 defineOptions({ name: "MultiLevel1" });
+
+onMounted(() => {
+  console.log("MultiLevel1 mounted");
+});
 </script>