feat(web): 新增控制台布局切换并完善状态与磁盘交互

新增经典、悬浮和侧栏布局，保存用户偏好，并调整工具栏、状态摘要及窄屏交互。
统一控制台弹层外观、焦点行为和中英文文案。
根据虚拟磁盘文件访问能力显示浏览入口、容量信息和不可用状态。

验证：npm run build 通过（vue-tsc 类型检查和 Vite 生产构建）。

web/src/composables/useConsoleLayout.ts

@@ -0,0 +1,32 @@
+import { ref, watch } from 'vue'
+
+export type ConsoleLayout = 'current' | 'floating' | 'sidebar'
+
+const STORAGE_KEY = 'consoleLayout'
+const VALID_LAYOUTS: ConsoleLayout[] = ['current', 'floating', 'sidebar']
+
+function readStoredLayout(): ConsoleLayout {
+  const stored = localStorage.getItem(STORAGE_KEY)
+  return VALID_LAYOUTS.includes(stored as ConsoleLayout)
+    ? stored as ConsoleLayout
+    : 'current'
+}
+
+const consoleLayout = ref<ConsoleLayout>(readStoredLayout())
+
+watch(consoleLayout, layout => {
+  localStorage.setItem(STORAGE_KEY, layout)
+})
+
+export function useConsoleLayout() {
+  function setConsoleLayout(layout: ConsoleLayout) {
+    if (VALID_LAYOUTS.includes(layout)) {
+      consoleLayout.value = layout
+    }
+  }
+
+  return {
+    consoleLayout,
+    setConsoleLayout,
+  }
+}