feat(阶段1): 搬入 ojnext 为 apps/web，未改业务代码

apps/web/src/oj/composables/syncStatus.ts

@@ -0,0 +1,73 @@
+import { ref, provide, inject } from "vue"
+
+/**
+ * 同步状态管理 composable
+ * 使用 provide/inject 模式在组件树中共享状态
+ */
+
+export interface SyncStatusState {
+  hadConnection: boolean
+  otherUser?: { name: string; isSuperAdmin: boolean }
+  lastLeftUser?: { name: string; isSuperAdmin: boolean } // 保存离开之人的信息
+}
+
+// 提供/注入的 key
+export const SYNC_STATUS_KEY = Symbol("syncStatus")
+
+/**
+ * 创建同步状态实例
+ * 每次调用创建新的状态实例
+ */
+export function createSyncStatus() {
+  const otherUser = ref<{ name: string; isSuperAdmin: boolean }>()
+  const hadConnection = ref(false)
+  const lastLeftUser = ref<{ name: string; isSuperAdmin: boolean }>()
+
+  const setOtherUser = (user?: { name: string; isSuperAdmin: boolean }) => {
+    // 如果之前有其他用户，现在没有了，说明用户离开了
+    if (otherUser.value && !user) {
+      lastLeftUser.value = otherUser.value
+    }
+    otherUser.value = user
+    if (user) {
+      hadConnection.value = true
+    }
+  }
+
+  const reset = () => {
+    otherUser.value = undefined
+    hadConnection.value = false
+    lastLeftUser.value = undefined
+  }
+
+  return {
+    otherUser,
+    hadConnection,
+    lastLeftUser,
+    setOtherUser,
+    reset,
+  }
+}
+
+/**
+ * 提供同步状态到子组件
+ * 在父组件中调用
+ */
+export function provideSyncStatus() {
+  const syncStatus = createSyncStatus()
+  provide(SYNC_STATUS_KEY, syncStatus)
+  return syncStatus
+}
+
+/**
+ * 注入同步状态
+ * 在子组件中调用，获取父组件提供的状态
+ */
+export function injectSyncStatus() {
+  const syncStatus =
+    inject<ReturnType<typeof createSyncStatus>>(SYNC_STATUS_KEY)
+  if (!syncStatus) {
+    throw new Error("syncStatus must be provided by a parent component")
+  }
+  return syncStatus
+}