feat(income-curve): wire chartRef + onChartComplete placeholder

frontend/pages/dashboard/components/IncomeCurve.vue

@@ -21,6 +21,7 @@
     <view v-else class="chart-wrap">
       <view class="chart-canvas">
         <qiun-data-charts
+          ref="chartRef"
           type="area"
           :opts="chartOpts"
           :chartData="chartData"
@@ -33,6 +34,7 @@
           :canvasHeight="240"
           ontap
           @tap="onChartTap"
+          @complete="onChartComplete"
         />
       </view>
     </view>
@@ -40,7 +42,7 @@
 </template>
 
 <script setup>
-import { computed, ref, watch } from "vue";
+import { computed, nextTick, ref, watch } from "vue";
 // 显式 import 兜底，避免 easycom 漏注册
 import QiunDataCharts from "@/uni_modules/qiun-data-charts/components/qiun-data-charts/qiun-data-charts.vue";
 
@@ -51,6 +53,16 @@ const props = defineProps({
 });
 defineEmits(["retry"]);
 
+// [新增] 拿到 qiun-data-charts 实例，用于首次渲染后触发默认 tooltip
+const chartRef = ref(null);
+// [新增] 上次已展示 tooltip 的数据点数量，避免重复触发
+const lastShownLen = ref(0);
+
+// [新增] 图表首次渲染完成回调（占位，Task 2 填充真实逻辑）
+const onChartComplete = (_e) => {
+  // 故意留空 — Task 2 接入 fake event 触发
+};
+
 // 当前选中的数据点索引：默认指向最后一条，tap 时更新
 const currentIndex = ref(0);
 watch(