feat: 战略地图贝塞尔因果链+节点KPI可视化(P0+P1)

frontend/src/components/map-canvas/MapCanvasToolbar.vue

@@ -23,6 +23,12 @@
           <input type="radio" :checked="viewDirection === 'causal'" @change="$emit('update:viewDirection', 'causal')" /> 🔗 因果
         </label>
       </span>
+      <el-button
+        :type="chainMode ? 'warning' : 'default'"
+        :class="{ 'chain-mode-on': chainMode }"
+        @click="$emit('toggle-chain-mode')"
+        title="点击节点可聚焦查看其相关因果链，其余自动变淡"
+      >🔍 因果链查看{{ chainMode ? '中' : '' }}</el-button>
       <el-button @click="$emit('show-causality')">🔗 因果链推荐</el-button>
       <el-button type="primary" @click="$emit('save-canvas')">保存</el-button>
       <el-button type="success" @click="$emit('publish-map')" v-if="currentMap?.status === 'draft'">发布</el-button>
@@ -54,6 +60,7 @@ const props = defineProps<{
   viewDirection: string
   currentMap: any
   linkingFrom: { key: string; obj: any } | null
+  chainMode: boolean
 }>()
 
 const emit = defineEmits<{
@@ -70,6 +77,7 @@ const emit = defineEmits<{
   (e: 'show-versions'): void
   (e: 'go-alignment'): void
   (e: 'cancel-link'): void
+  (e: 'toggle-chain-mode'): void
 }>()
 
 const selectedMapLocal = ref(props.selectedMap)