新增消息已读状态

复用 chat_participants.last_read_at 推导已读，无需新表/迁移。

- 后端：MessageDTO 增加 is_read，toMessageDTOs 按「全部已读」语义计算
  （所有其他参与者均已读才算已读，1对1 即对方已读）；MarkRead 成功后
  推送 conversation_read 事件（含 reader 与 read_at），NotifyConversation
  与 NotifyAllAdmins 双通道通知，使发送方/客服实时刷新已读
- 前端：ChatMessage 增加 is_read，ChatView/AdminChatsView/MobileChatView
  在自己的消息下渲染「已读/未读」；收到 conversation_read 且本端仍有
  未获回执的自己消息时才重载，避免无谓请求

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/features/admin/views/AdminChatsView.vue

@@ -71,6 +71,15 @@ function handleSSEEvent(event: ChatEvent) {
   if (event.type === 'conversation_updated') {
     loadConversations(false)
   }
+  if (event.type === 'conversation_read') {
+    // 对方已读：仅当本端仍有未获回执的自己消息时重载，刷新「已读」状态
+    if (active.value && event.conversation_id === active.value.id) {
+      const isSelfReader = event.reader_type === 'admin' && event.reader_id === currentAdminId
+      if (!isSelfReader && messages.value.some(m => m.is_self && !m.is_read)) {
+        loadMessages(active.value.id, false)
+      }
+    }
+  }
   if (event.type === 'new_message') {
     const msg = event.message
     if (!msg) return
@@ -91,6 +100,7 @@ function handleSSEEvent(event: ChatEvent) {
           sender_name: msg.sender_name,
           sender_avatar: '',
           is_self: isSelf,
+          is_read: false,
           content_type: msg.content_type as ChatMessage['content_type'],
           content: msg.content,
           attachment_urls: msg.attachment_urls || [],
@@ -441,6 +451,9 @@ function getSupportName(item: ChatConversation) {
                     admin
                   />
                 </div>
+                <small v-if="item.is_self" class="read-status" :class="{ read: item.is_read }">
+                  {{ item.is_read ? '已读' : '未读' }}
+                </small>
               </template>
             </div>
           </div>
@@ -729,6 +742,16 @@ function getSupportName(item: ChatConversation) {
   color: #8a94a6;
 }
 
+.read-status {
+  margin-top: 4px;
+  margin-bottom: 0;
+  font-size: 11px;
+}
+
+.read-status.read {
+  color: #67c23a;
+}
+
 .message-row p {
   display: inline-block;
   margin: 0;

frontend/src/features/chats/api/chats.ts

@@ -39,6 +39,7 @@ export interface ChatMessage {
   sender_name: string
   sender_avatar: string
   is_self: boolean
+  is_read: boolean
   content_type: 'text' | 'system'
   content: string
   attachment_urls: string[]

frontend/src/features/chats/composables/useChatSSE.ts

@@ -16,9 +16,12 @@ export interface SSEMessage {
 }
 
 export interface ChatEvent {
-  type: 'new_message' | 'conversation_updated'
+  type: 'new_message' | 'conversation_updated' | 'conversation_read'
   conversation_id: number
   message?: SSEMessage
+  reader_type?: string
+  reader_id?: number
+  read_at?: string
 }
 
 type EventHandler = (event: ChatEvent) => void
@@ -69,6 +72,15 @@ export function useChatSSE(scope: AuthScope, endpoint: string) {
       }
     })
 
+    source.addEventListener('conversation_read', e => {
+      try {
+        const data = JSON.parse((e as MessageEvent).data) as ChatEvent
+        handlers.forEach(h => h(data))
+      } catch {
+        /* ignore */
+      }
+    })
+
     source.onerror = async () => {
       connected.value = false
       source?.close()

frontend/src/features/chats/views/ChatView.vue

@@ -58,6 +58,7 @@ function handleSSEEvent(event: ChatEvent) {
           sender_name: msg.sender_name,
           sender_avatar: '',
           is_self: isSelf,
+          is_read: false,
           content_type: msg.content_type as ChatMessage['content_type'],
           content: msg.content,
           attachment_urls: msg.attachment_urls || [],
@@ -76,6 +77,13 @@ function handleSSEEvent(event: ChatEvent) {
   if (event.type === 'conversation_updated' && event.conversation_id === conversationID.value) {
     loadConversation()
   }
+  if (event.type === 'conversation_read' && event.conversation_id === conversationID.value) {
+    // 对方已读：仅当本端仍有未获回执的自己消息时重载，刷新「已读」状态
+    const isSelfReader = event.reader_type === 'user' && event.reader_id === currentUserId
+    if (!isSelfReader && messages.value.some(m => m.is_self && !m.is_read)) {
+      loadMessages(false)
+    }
+  }
 }
 
 const { onEvent } = useChatSSE('user', '/api/chats/events')
@@ -305,6 +313,9 @@ function handleKeydown(e: KeyboardEvent) {
                 <ChatAttachmentImage v-for="url in item.attachment_urls" :key="url" :source="url" />
               </div>
               <span class="message-time">{{ formatDateMinute(item.created_at) }}</span>
+              <span v-if="item.is_self" class="read-status" :class="{ read: item.is_read }">
+                {{ item.is_read ? '已读' : '未读' }}
+              </span>
             </div>
           </template>
         </div>
@@ -538,6 +549,16 @@ function handleKeydown(e: KeyboardEvent) {
   font-size: 11px;
 }
 
+.read-status {
+  margin-top: 2px;
+  color: #a1a8b4;
+  font-size: 11px;
+}
+
+.read-status.read {
+  color: #67c23a;
+}
+
 .system-message {
   max-width: 80%;
   padding: 6px 12px;

frontend/src/features/chats/views/MobileChatView.vue

@@ -62,6 +62,7 @@ function handleSSEEvent(event: ChatEvent) {
             sender_name: msg.sender_name,
             sender_avatar: '',
             is_self: isSelf,
+            is_read: false,
             content_type: msg.content_type as ChatMessage['content_type'],
             content: msg.content,
             attachment_urls: msg.attachment_urls || [],
@@ -80,6 +81,13 @@ function handleSSEEvent(event: ChatEvent) {
   if (event.type === 'conversation_updated' && event.conversation_id === conversationID.value) {
     loadConversation()
   }
+  if (event.type === 'conversation_read' && event.conversation_id === conversationID.value) {
+    // 对方已读：仅当本端仍有未获回执的自己消息时重载，刷新「已读」状态
+    const isSelfReader = event.reader_type === 'user' && event.reader_id === currentUserId
+    if (!isSelfReader && messages.value.some(m => m.is_self && !m.is_read)) {
+      loadMessages(false)
+    }
+  }
 }
 
 const { onEvent } = useChatSSE('user', '/api/chats/events')
@@ -284,6 +292,9 @@ function senderLabel(message: ChatMessage) {
               <ChatAttachmentImage v-for="url in item.attachment_urls" :key="url" :source="url" />
             </div>
             <span class="message-time">{{ formatDateMinute(item.created_at) }}</span>
+            <span v-if="item.is_self" class="read-status" :class="{ read: item.is_read }">
+              {{ item.is_read ? '已读' : '未读' }}
+            </span>
           </div>
         </template>
       </div>
@@ -499,6 +510,16 @@ function senderLabel(message: ChatMessage) {
   font-size: 10px;
 }
 
+.read-status {
+  margin-top: 2px;
+  color: #a1a8b4;
+  font-size: 10px;
+}
+
+.read-status.read {
+  color: #67c23a;
+}
+
 .system-message {
   max-width: 82%;
   padding: 5px 9px;