fix: 级联/因果视角切换 — 跨层箭头方向+SVG三角+ConnectionLines联动

frontend/src/views/MapCanvas.vue

@@ -92,11 +92,12 @@
             @reorder="(dk: string) => onLayerReorder(dk)"
           />
 
-          <!-- 跨层箭头指示器（本层→下层） -->
+          <!-- 跨层箭头指示器（根据视角切换方向） -->
           <div v-if="idx < orderedLayerConfigs.length - 1" class="cross-layer-arrow">
             <svg width="24" height="32" viewBox="0 0 24 32">
               <line x1="12" y1="0" x2="12" y2="24" stroke="#909399" stroke-width="2" stroke-dasharray="4,3" />
-              <polygon points="4,22 12,30 20,22" fill="#909399" />
+              <polygon v-if="viewDirection === 'cascade'" points="4,22 12,30 20,22" fill="#909399" />
+              <polygon v-else points="4,8 12,0 20,8" fill="#909399" />
             </svg>
           </div>
         </div>
@@ -107,11 +108,12 @@
     <ConnectionLines
       ref="connectionLinesRef"
       :layer-refs="layerRefs"
-      :node-refs="nodeRefs"
+      :node-refs="compiledNodeRefs"
       :layer-keys="layerKeysOrdered"
       :connections="connections"
       :temp-line="tempLine"
       :container-key="recalcTrigger"
+      :view-direction="viewDirection"
       @select-connection="onSelectConnection"
       @delete-connection="onDeleteConnection"
     />