feat(aiot): Edge截图方案替代ZLM截图，支持COS URL返回

- 新增 IAiScreenshotService 接口和实现：通过 Redis Stream 请求 Edge
  截图，轮询等待结果，支持 5 分钟缓存和 force 刷新
- AiRoiController.getSnap() 从 ZLM 二进制截图改为返回 JSON（含 COS URL）
- 前端 aiRoi.js 新增 getSnapUrl 方法
- roiConfig.vue 改为异步加载截图，增加 loading 状态和错误提示

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/api/aiRoi.js

@@ -62,3 +62,11 @@ export function updateAlgoParams(data) {
     data: data
   })
 }
+
+export function getSnapUrl(cameraCode, force = false) {
+  return request({
+    method: 'get',
+    url: '/api/ai/roi/snap',
+    params: { cameraCode, force }
+  })
+}

web/src/views/cameraConfig/roiConfig.vue

@@ -8,7 +8,7 @@
       <div class="header-right">
         <el-button size="small" type="primary" icon="el-icon-plus" @click="startDraw('rectangle')">画矩形</el-button>
         <el-button size="small" type="primary" icon="el-icon-plus" @click="startDraw('polygon')">画多边形</el-button>
-        <el-button size="small" icon="el-icon-refresh" @click="refreshSnap">刷新截图</el-button>
+        <el-button size="small" icon="el-icon-refresh" :loading="snapLoading" @click="refreshSnap">刷新截图</el-button>
         <el-button size="small" type="info" @click="handlePush">推送到边缘端</el-button>
       </div>
     </div>
@@ -87,7 +87,7 @@
 <script>
 import RoiCanvas from '@/views/roiConfig/components/RoiCanvas.vue'
 import RoiAlgorithmBind from '@/views/roiConfig/components/RoiAlgorithmBind.vue'
-import { queryRoiByCameraId, saveRoi, deleteRoi, queryRoiDetail } from '@/api/aiRoi'
+import { queryRoiByCameraId, saveRoi, deleteRoi, queryRoiDetail, getSnapUrl } from '@/api/aiRoi'
 import { pushConfig } from '@/api/aiConfig'
 
 export default {
@@ -103,7 +103,8 @@ export default {
       roiList: [],
       selectedRoiId: null,
       selectedRoiBindings: [],
-      snapUrl: ''
+      snapUrl: '',
+      snapLoading: false
     }
   },
   computed: {
@@ -117,7 +118,7 @@ export default {
     this.srcUrl = this.$route.query.srcUrl || ''
     this.app = this.$route.query.app || ''
     this.stream = this.$route.query.stream || ''
-    this.buildSnapUrl()
+    this.fetchSnap()
     this.loadRois()
   },
   methods: {
@@ -146,14 +147,29 @@ export default {
     startDraw(mode) {
       this.drawMode = mode
     },
-    buildSnapUrl() {
-      if (this.app && this.stream) {
-        const base = process.env.NODE_ENV === 'development' ? process.env.VUE_APP_BASE_API : ''
-        this.snapUrl = `${base}/api/ai/roi/snap?app=${encodeURIComponent(this.app)}&stream=${encodeURIComponent(this.stream)}&t=${Date.now()}`
-      }
+    fetchSnap(force = false) {
+      if (!this.cameraId) return
+      this.snapLoading = true
+      getSnapUrl(this.cameraId, force).then(res => {
+        const data = res.data || res
+        if (data.status === 'ok' && data.url) {
+          this.snapUrl = data.url
+          if (data.stale) {
+            this.$message.warning('截图为缓存数据，边缘设备可能离线')
+          }
+        } else if (data.status === 'timeout') {
+          this.$message.warning(data.message || '边缘设备响应超时')
+        } else {
+          this.$message.error(data.message || '截图失败')
+        }
+      }).catch(() => {
+        this.$message.error('截图请求失败，请检查网络')
+      }).finally(() => {
+        this.snapLoading = false
+      })
     },
     refreshSnap() {
-      this.buildSnapUrl()
+      this.fetchSnap(true)
     },
     onRoiDrawn(data) {
       this.drawMode = null