fix(前端)：进度环方向 + 按钮颜色 + 删除确认 + 移除 console.log

- StartTask.vue：progress 计算改为 (total-current)/total*100，进度环从
  满到空递减（正确方向）
- ReviewDetail/ReviewRecall/MindMapViewer：type="primary" 全部改为
  type="success"，统一绿白主题
- Study.vue：删除任务增加 ElMessageBox.confirm 确认
- request.ts：移除全部 console.log

src/components/Study.vue

@@ -2,7 +2,7 @@
 import { computed, onMounted, ref, watch } from "vue";
 import request from "@/utils/request";
 import router from "@/router";
-import { ElMessage } from "element-plus";
+import { ElMessage, ElMessageBox } from "element-plus";
 import { getReviewTaskStatsByTask } from "@/api/review";
 import {
   getPriorityWeights,
@@ -185,6 +185,15 @@ const removeTask = async () => {
     return;
   }
   const target = selectedTask.value;
+  try {
+    await ElMessageBox.confirm(`确定删除任务「${target.title}」？关联的学习会话、学习报告、应用场景等数据将被一并删除。`, "确认删除", {
+      confirmButtonText: "确定删除",
+      cancelButtonText: "取消",
+      type: "warning",
+    });
+  } catch {
+    return; // 用户取消
+  }
   const res = await request.del(`/tasks/${target.taskId}`, {});
   if (res.code === 200) {
     ElMessage.success(`任务 ${target.title} 删除成功`);