fix(mobile): stack supervisor learner-mode banner title and stop button squeeze

The inline panel-title ran into the description text and the bordered
return button was compressed into an ugly two-line wrap; give the copy
column block layout and keep the action button on one line.

mobile-uni/src/pages/user/profile/index.vue

@@ -23,8 +23,8 @@
     </view>
 
     <view v-if="supervisorLearning" class="panel supervisor-mode-panel">
-      <view>
-        <text class="panel-title">当前为学员模式</text>
+      <view class="mode-copy">
+        <text class="panel-title mode-title">当前为学员模式</text>
         <text class="identity-source">主管组织身份未改变，仅切换到个人学习与训练界面。</text>
       </view>
       <button class="secondary-button account-action" @click="returnToSupervisor">返回主管工作台</button>
@@ -480,9 +480,25 @@ onShow(() => {
   gap: 12px;
 }
 
+.mode-copy {
+  flex: 1;
+  min-width: 0;
+}
+
+.mode-title {
+  display: block;
+}
+
+.mode-copy .identity-source {
+  display: block;
+}
+
 .account-action {
-  min-width: 84px;
-  padding: 0 12px;
+  flex-shrink: 0;
+  min-width: 0;
+  padding: 0 14px;
+  white-space: nowrap;
+  font-size: 15px;
 }
 
 .display-panel {